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digitspace
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Week 01算法题
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‎Week_01/G20200343030569/LeetCode_189_569.java‎

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/*
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* 189.Rotate Array
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* 旋转数组
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*/
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public class LeetCode_189_569 {
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public static void main(String[] args) {
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int[] nums = { 1,2,3,4,5,6,7 };
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int k = 4;
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(new LeetCode_189_569()).new Solution().rotate(nums,k);
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for( int i = 0; i < nums.length; i++ ){
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System.out.println(nums[i]);
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}
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}
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class Solution {
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public void rotate(int[] nums, int k) {
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k = k % nums.length;
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for (int i = 0, count = 0; count < nums.length; i++) {
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int source = i;
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int sourceValue = nums[source];
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do {
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int dest = (source + k) % nums.length;
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int temp = nums[dest];
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nums[dest] = sourceValue;
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source = dest;
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sourceValue = temp;
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count++;
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} while (source != i);
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}
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}
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}
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}
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‎Week_01/G20200343030569/LeetCode_1_569.java‎

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import java.util.HashMap;
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import java.util.Map;
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/*
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* 1. Two Sum
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* 两数之和
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*/
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public class LeetCode_1_569 {
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public static void main(String[] args) {
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// TODO Auto-generated method stub
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int[] nums = { 12,2,7,11,15 };
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int target = 9;
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int[] n = (new LeetCode_1_569()).new Solution().twoSum(nums, target);
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for( int i = 0; i < n.length; i++ ){
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System.out.println(n[i]);
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}
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}
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class Solution {
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public int[] twoSum(int[] nums, int target) {
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Map<Integer,Integer> map = new HashMap<Integer,Integer>();
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for (int i = 0; i < nums.length; i++) {
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int want = target - nums[i];
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if( map.containsKey(want) ) {
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return new int[] { map.get(want), i };
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}
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map.put(nums[i], i);
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}
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return null;
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}
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}
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}

‎Week_01/G20200343030569/LeetCode_21_569.java‎

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/*
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* 21. Merge Two Sorted Lists
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* 合并两个有序链表
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*/
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public class LeetCode_21_569 {
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public static void main(String[] args) {
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LeetCode_21_569 lc = new LeetCode_21_569();
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ListNode ln13 = lc.createNewNode(4, null);
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ListNode ln12 = lc.createNewNode(2, ln13);
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ListNode ln11 = lc.createNewNode(1, ln12);
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ListNode ln23 = lc.createNewNode(4, null);
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ListNode ln22 = lc.createNewNode(3, ln23);
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ListNode ln21 = lc.createNewNode(1, ln22);
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ListNode node = lc.new Solution().mergeTwoLists(ln11,ln21);
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while (node != null) {
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System.out.println(node.val);
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node = node.next;
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}
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}
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public ListNode createNewNode( int i, ListNode next ) {
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ListNode node = new ListNode(i);
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node.next = next;
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return node;
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}
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public class ListNode {
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int val;
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ListNode next;
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ListNode(int x) { val = x; }
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}
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class Solution {
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public ListNode mergeTwoLists(ListNode l1, ListNode l2) {
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ListNode tempNode = new ListNode(0);
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ListNode currentNode = tempNode;
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while (l1 != null && l2 != null) {
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currentNode.next = (l1.val < l2.val) ? l1 : l2;
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ListNode n = (l1.val < l2.val) ? (l1 = l1.next) : (l2 = l2.next);
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currentNode = currentNode.next;
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}
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ListNode nonEmpty = (l1 != null) ? l1 : l2;
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currentNode.next = nonEmpty;
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return tempNode.next;
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}
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}
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}

‎Week_01/G20200343030569/LeetCode_26_569.java‎

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/*
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* 26. Remove Duplicates from Sorted Array
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* 删除排序数组中的重复项
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*/
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public class LeetCode_26_569 {
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public static void main( String[] argv) {
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int[] nums = { 0,0,1,1,1,2,2,3,3,4,4 };
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int n = (new LeetCode_26_569()).new Solution().removeDuplicates(nums);
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for( int i = 0; i < n; i++ ){
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System.out.println(nums[i]);
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}
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}
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class Solution {
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public int removeDuplicates(int[] nums) {
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if (nums.length <= 1)
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return nums.length;
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int validIndex = 1;
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int lastNum = nums[0];
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for (int i = 1; i < nums.length; i++) {
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if (nums[i] != lastNum) {
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nums[validIndex++] = nums[i];
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lastNum = nums[i];
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}
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}
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return validIndex;
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}
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}
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}
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‎Week_01/G20200343030569/LeetCode_283_569.java‎

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/*
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* 283. Move Zeroes
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* 移动零
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*/
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public class LeetCode_283_569 {
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public static void main(String[] args) {
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int[] nums = { 0,1,0,3,12,0 };
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int target = 9;
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(new LeetCode_283_569()).new Solution().moveZeroes(nums);
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for( int i = 0; i < nums.length; i++ ){
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System.out.println(nums[i]);
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}
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}
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class Solution {
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public void moveZeroes(int[] nums) {
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int validIndex = 0;
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for ( int i = 0; i < nums.length; i++ ) {
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if ( nums[i] != 0 ) {
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nums[validIndex++] = nums[i];
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nums[i] = 0;
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}
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}
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}
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}
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}

‎Week_01/G20200343030569/LeetCode_42_569.java‎

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/*
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* 42. Trapping Rain Water
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* 接雨水
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*/
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public class LeetCode_42_569 {
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public static void main(String[] args) {
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// TODO Auto-generated method stub
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int[] nums = { 2,0,2 };
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int n = (new LeetCode_42_569()).new Solution().trap(nums);
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System.out.println(n);
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}
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class Solution {
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/*
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* 按行算水量，行数等于高度数组的最大值，但这个算法对于高度高的数组超时，比较垃圾
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*/
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public int trap(int[] height) {
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int water = 0;
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int rows = 0;
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for (int i:height) {
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rows = Math.max(rows, i);
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}
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//遍历每行
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for ( int i = 1; i <= rows; i++ ) {
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int rowWater = 0;
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int left = -1;
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int right = -1;
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for ( int j = 0; j < height.length; j++ ) {
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if ( height[j] >= i ) {
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if ( left < 0 ) { //第一个left
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left = j;
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}else {
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if ( j == left + 1 ) {
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left = j;
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}else {
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right = j;
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rowWater = rowWater + (right - left - 1);
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left = right;
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right = -1;
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}
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}
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}
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}
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water += rowWater;
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}
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return water;
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}
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}
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}

‎Week_01/G20200343030569/LeetCode_641_569.java‎

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/*
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* 641. Design Circular Deque
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* 设计循环双端队列
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*/
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public class LeetCode_641_569 {
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public static void main(String[] args) {
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MyCircularDeque circularDeque = new MyCircularDeque(8);
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circularDeque.insertFront(5);
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circularDeque.getFront();
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circularDeque.isEmpty();
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circularDeque.deleteFront();
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circularDeque.insertLast(3);
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circularDeque.getRear();
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circularDeque.insertLast(7);
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circularDeque.insertFront(7);
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circularDeque.deleteLast();
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circularDeque.insertLast(4);
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circularDeque.isEmpty();
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/*circularDeque.insertFront(1);
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circularDeque.insertLast(2);
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circularDeque.getFront();
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circularDeque.insertLast(3);
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circularDeque.getFront();
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circularDeque.insertFront(5);
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circularDeque.getRear();
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circularDeque.getFront();
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circularDeque.getFront();
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circularDeque.deleteLast();
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circularDeque.getRear();*/
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/* circularDeque.insertLast(1); // 返回 true
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circularDeque.insertLast(2); // 返回 true
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circularDeque.insertFront(3); // 返回 true
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circularDeque.insertFront(4); // 已经满了，返回 false
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circularDeque.getRear(); // 返回 2
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circularDeque.isFull(); // 返回 true
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circularDeque.deleteLast(); // 返回 true
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circularDeque.insertFront(4); // 返回 true
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circularDeque.getFront(); // 返回 4
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*/
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}
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}
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class MyCircularDeque {
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class Node {
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Node prev;
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int value;
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Node next;
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Node( Node prev, int value, Node next) {
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this.prev = prev;
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this.value = value;
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this.next = next;
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}
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}
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int maxSize;
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int size;
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Node head;
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Node tail;
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public MyCircularDeque(int k) {
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this.maxSize = k;
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}
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public boolean insertFront(int value) {
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if ( size == maxSize )
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return false;
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Node n = new Node( null, value, head );
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if ( head == null )
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tail = n;
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else
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head.prev = n;
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head = n;
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size++;
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return true;
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}
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public boolean insertLast(int value) {
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if ( size == maxSize )
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return false;
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Node n = new Node( tail, value, null );
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if ( tail == null )
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head = n;
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else
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tail.next = n;
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tail = n;
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size++;
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return true;
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}
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public boolean deleteFront() {
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if ( head == null )
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return false;
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Node n = head;
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Node next = head.next;
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n.next = null;
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head = next;
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if ( head != null )
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head.prev = null;
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else
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tail = null;
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size--;
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return true;
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}
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public boolean deleteLast() {
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if ( tail == null )
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return false;
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Node n = tail;
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Node prev = tail.prev;
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n.prev = null;
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tail = prev;
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if ( tail != null )
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tail.next = null;
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else
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head = null;
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size--;
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return true;
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}
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public int getFront() {
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return (size==0) ? -1 : head.value;
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}
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public int getRear() {
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return (size==0) ? -1 : tail.value;
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}
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public boolean isEmpty() {
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return (size == 0);
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}
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public boolean isFull() {
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return (size == maxSize);
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}
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}

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