307 solved

README.md

@@ -114,6 +114,7 @@ continually updating 😃.
 * [226. Invert Binary Tree](src/0226_invert_binary_tree/invert_binary_tree.go)   *`binary tree;`*
 * [235. Lowest Common Ancestor of a Binary Search Tree](src/0235_lowest_common_ancestor_of_a_binary_search_tree/lcaoabst.go)   *`binary tree;`*
 * [257. Binary Tree Paths](src/0257_binary_tree_paths/binary_tree_paths.go)   *`binary tree`*
+* [307. Range Sum Query - Mutable](src/0307_Range_Sum_Query_Mutable/range_sum_query_mut.go)   *`segment tree`*
 * [404. Sum of Left Leaves](src/0404_sum_of_left_leaves/sum_of_left_leaves.go)   *`binary tree`*
 * [437. Path Sum III](src/0437_path_sum_3/path_sum_3.go)   *`binary tree`*
 * [872. Leaf-Similar Trees](src/0872_leaf_similar_trees/leaf_similar_trees.go)   *`binary tree`*

src/0307_Range_Sum_Query_Mutable/range_sum_query_mut.go

@@ -0,0 +1,88 @@
+/*
+307. Range Sum Query - Mutable
+https://leetcode.com/problems/range-sum-query-mutable/
+
+Given an integer array nums, find the sum of the elements between indices i and j (i ≤ j), inclusive.
+
+The update(i, val) function modifies nums by updating the element at index i to val.
+
+Note:
+The array is only modifiable by the update function.
+You may assume the number of calls to update and sumRange function is distributed evenly.
+*/
+// time: 2019-01-29
+// 线段树时间复杂度为：O(log n)
+
+package rsqm
+
+// NumArray 线段树
+type NumArray struct {
+	segmentTree []int
+	data        []int
+}
+
+// Constructor 线段树生成函数
+func Constructor(nums []int) NumArray {
+	na := NumArray{segmentTree: make([]int, len(nums)*4), data: nums[:]}
+	na.buildSegmentTree(0, 0, len(na.data)-1)
+	return na
+}
+
+func (na *NumArray) buildSegmentTree(treeIndex, left, right int) {
+	// 线段树处理的数据不能为空。
+	//if right < left {
+	//	return
+	//}
+	if left == right {
+		na.segmentTree[treeIndex] = na.data[left]
+		return
+	}
+	mid := left + (right-left)>>1
+	leftTreeIndex := 2*treeIndex + 1
+	rightTreeIndex := 2*treeIndex + 2
+	na.buildSegmentTree(leftTreeIndex, left, mid)
+	na.buildSegmentTree(rightTreeIndex, mid+1, right)
+	na.segmentTree[treeIndex] = na.segmentTree[leftTreeIndex] + na.segmentTree[rightTreeIndex]
+}
+
+// Update 线段树更新操作。
+func (na *NumArray) Update(i int, val int) {
+	na.setter(0, 0, len(na.data)-1, i, val)
+}
+
+func (na *NumArray) setter(treeIndex, left, right, index, val int) {
+	if left == right {
+		na.segmentTree[treeIndex] = val
+		return
+	}
+	mid := left + (right-left)>>1
+	leftTreeIndex := 2*treeIndex + 1
+	rightTreeIndex := 2*treeIndex + 2
+	if index >= mid+1 {
+		na.setter(rightTreeIndex, mid+1, right, index, val)
+	} else {
+		na.setter(leftTreeIndex, left, mid, index, val)
+	}
+	na.segmentTree[treeIndex] = na.segmentTree[leftTreeIndex] + na.segmentTree[rightTreeIndex]
+}
+
+// SumRange 线段树查询
+func (na *NumArray) SumRange(i int, j int) int {
+	return na.query(0, 0, len(na.data)-1, i, j)
+}
+
+func (na *NumArray) query(treeIndex, left, right, queryL, queryR int) int {
+	if left == queryL && right == queryR {
+		return na.segmentTree[treeIndex]
+	}
+	mid := left + (right-left)>>1
+	leftTreeIndex := 2*treeIndex + 1
+	rightTreeIndex := 2*treeIndex + 2
+	if queryL >= mid+1 {
+		return na.query(rightTreeIndex, mid+1, right, queryL, queryR)
+	} else if queryR <= mid {
+		return na.query(leftTreeIndex, left, mid, queryL, queryR)
+	} else {
+		return na.query(leftTreeIndex, left, mid, queryL, mid) + na.query(rightTreeIndex, mid+1, right, mid+1, queryR)
+	}
+}

src/0307_Range_Sum_Query_Mutable/range_sum_query_mut_test.go

@@ -0,0 +1,15 @@
+package rsqm
+
+import "testing"
+
+func TestNumArray(t *testing.T) {
+	nums := []int{1, 2, 3, 6, 7, 8, 9, 3, 4, 2, 5}
+	na := Constructor(nums)
+	if res := na.SumRange(4, 9); res != 33 {
+		t.Errorf("expected %d, got %d", 43, res)
+	}
+	na.Update(6, 10)
+	if res := na.SumRange(4, 9); res != 34 {
+		t.Errorf("expected %d, got %d", 44, res)
+	}
+}

src/README.md

@@ -80,6 +80,7 @@
 |0283|[Move Zeroes(solution1)](./0283_move_zeroes/move_zeroes.go) <br/>  [Move Zeroes(solution2)](./0283_move_zeroes/move_zeroes2.go)|Easy|*`array`*|
 |0300|[Longest Increasing Subsequence](./0300_longest_increasing_subsequence/lis.go)|Medium|*`dp`*|
 |0303|[303. Range Sum Query - Immutable](0303_range_sum_query/rsqim.go)|Easy||
+|0307|[307. Range Sum Query - Mutable](0307_Range_Sum_Query_Mutable/range_sum_query_mut.go)|Medium|*`segment tree`*|
 |0328|[328. Odd Even Linked List](0328_odd_even_linked_list/odd_even_linked_list.go)|Medium|*`singly linked list`*|
 |0343|[Integer Break](./0343_integer_break/integer_break.go)|Medium|*`recursion;`* *`memory search;`* *`dynamic programming`*|
 |0344|[344. Reverse String](0344_reverse_string/reverse_string.go)|Easy|*`double index`*|