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feat: add solutions to lc problem: No.1670. Design Front Middle Back Queue
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‎solution/1600-1699/1670.Design Front Middle Back Queue/README.md

+140-3
Original file line numberDiff line numberDiff line change
@@ -60,27 +60,164 @@ q.popFront(); // 返回 -1 -> [] （队列为空）
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<li>最多调用 <code>1000</code> 次 <code>pushFront</code>， <code>pushMiddle</code>， <code>pushBack</code>， <code>popFront</code>， <code>popMiddle</code> 和 <code>popBack</code> 。</li>
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</ul>
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## 解法
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<!-- 这里可写通用的实现逻辑 -->
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两个“双端队列”实现。
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<!-- tabs:start -->
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### **Python3**
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<!-- 这里可写当前语言的特殊实现逻辑 -->
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```python
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class FrontMiddleBackQueue:
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def __init__(self):
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self.left = collections.deque()
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self.right = collections.deque()
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def pushFront(self, val: int) -> None:
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self.left.appendleft(val)
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self.rebalance()
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def pushMiddle(self, val: int) -> None:
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self.left.append(val)
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self.rebalance()
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def pushBack(self, val: int) -> None:
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self.right.append(val)
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self.rebalance()
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def popFront(self) -> int:
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if self.empty():
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return -1
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if self.left:
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val = self.left.popleft()
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else:
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val = self.right.popleft()
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self.rebalance()
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return val
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def popMiddle(self) -> int:
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if self.empty():
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return -1
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if len(self.left) >= len(self.right):
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val = self.left.pop()
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else:
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val = self.right.popleft()
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self.rebalance()
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return val
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def popBack(self) -> int:
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if self.empty():
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return -1
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val = self.right.pop()
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self.rebalance()
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return val
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def empty(self) -> bool:
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return not self.left and not self.right
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def rebalance(self) -> None:
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while len(self.left) > len(self.right):
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self.right.appendleft(self.left.pop())
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while len(self.right) - len(self.left) > 1:
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self.left.append(self.right.popleft())
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# Your FrontMiddleBackQueue object will be instantiated and called as such:
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# obj = FrontMiddleBackQueue()
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# obj.pushFront(val)
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# obj.pushMiddle(val)
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# obj.pushBack(val)
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# param_4 = obj.popFront()
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# param_5 = obj.popMiddle()
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# param_6 = obj.popBack()
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```
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### **Java**
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<!-- 这里可写当前语言的特殊实现逻辑 -->
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```java
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class FrontMiddleBackQueue {
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private Deque<Integer> left;
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private Deque<Integer> right;
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public FrontMiddleBackQueue() {
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left = new LinkedList<>();
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right = new LinkedList<>();
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}
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public void pushFront(int val) {
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left.offerFirst(val);
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rebalance();
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}
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public void pushMiddle(int val) {
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left.offerLast(val);
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rebalance();
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}
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public void pushBack(int val) {
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right.offerLast(val);
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rebalance();
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}
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public int popFront() {
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if (empty()) {
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return -1;
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}
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int val = left.isEmpty() ? right.pollFirst() : left.pollFirst();
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rebalance();
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return val;
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}
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public int popMiddle() {
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if (empty()) {
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return -1;
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}
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int val = left.size() >= right.size() ? left.pollLast() : right.pollFirst();
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rebalance();
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return val;
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}
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public int popBack() {
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if (empty()) {
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return -1;
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}
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int val = right.pollLast();
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rebalance();
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return val;
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}
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private boolean empty() {
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return left.isEmpty() && right.isEmpty();
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}
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private void rebalance() {
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while (left.size() > right.size()) {
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right.offerFirst(left.pollLast());
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}
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while (right.size() - left.size() > 1) {
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left.offerLast(right.pollFirst());
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}
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}
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}
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/**
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* Your FrontMiddleBackQueue object will be instantiated and called as such:
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* FrontMiddleBackQueue obj = new FrontMiddleBackQueue();
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* obj.pushFront(val);
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* obj.pushMiddle(val);
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* obj.pushBack(val);
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* int param_4 = obj.popFront();
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* int param_5 = obj.popMiddle();
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* int param_6 = obj.popBack();
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*/
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```
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### **...**

‎solution/1600-1699/1670.Design Front Middle Back Queue/README_EN.md

+138-3
Original file line numberDiff line numberDiff line change
@@ -56,21 +56,156 @@ q.popFront(); // return -1 -&gt; [] (The queue is empty)
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<li>At most&nbsp;<code>1000</code>&nbsp;calls will be made to&nbsp;<code>pushFront</code>,&nbsp;<code>pushMiddle</code>,&nbsp;<code>pushBack</code>, <code>popFront</code>, <code>popMiddle</code>, and <code>popBack</code>.</li>
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</ul>
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## Solutions
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<!-- tabs:start -->
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### **Python3**
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```python
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class FrontMiddleBackQueue:
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def __init__(self):
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self.left = collections.deque()
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self.right = collections.deque()
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def pushFront(self, val: int) -> None:
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self.left.appendleft(val)
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self.rebalance()
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def pushMiddle(self, val: int) -> None:
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self.left.append(val)
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self.rebalance()
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def pushBack(self, val: int) -> None:
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self.right.append(val)
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self.rebalance()
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def popFront(self) -> int:
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if self.empty():
86+
return -1
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if self.left:
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val = self.left.popleft()
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else:
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val = self.right.popleft()
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self.rebalance()
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return val
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def popMiddle(self) -> int:
95+
if self.empty():
96+
return -1
97+
if len(self.left) >= len(self.right):
98+
val = self.left.pop()
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else:
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val = self.right.popleft()
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self.rebalance()
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return val
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def popBack(self) -> int:
105+
if self.empty():
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return -1
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val = self.right.pop()
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self.rebalance()
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return val
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def empty(self) -> bool:
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return not self.left and not self.right
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def rebalance(self) -> None:
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while len(self.left) > len(self.right):
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self.right.appendleft(self.left.pop())
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while len(self.right) - len(self.left) > 1:
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self.left.append(self.right.popleft())
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# Your FrontMiddleBackQueue object will be instantiated and called as such:
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# obj = FrontMiddleBackQueue()
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# obj.pushFront(val)
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# obj.pushMiddle(val)
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# obj.pushBack(val)
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# param_4 = obj.popFront()
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# param_5 = obj.popMiddle()
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# param_6 = obj.popBack()
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```
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### **Java**
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```java
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class FrontMiddleBackQueue {
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private Deque<Integer> left;
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private Deque<Integer> right;
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public FrontMiddleBackQueue() {
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left = new LinkedList<>();
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right = new LinkedList<>();
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}
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public void pushFront(int val) {
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left.offerFirst(val);
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rebalance();
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}
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public void pushMiddle(int val) {
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left.offerLast(val);
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rebalance();
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}
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public void pushBack(int val) {
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right.offerLast(val);
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rebalance();
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}
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public int popFront() {
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if (empty()) {
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return -1;
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}
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int val = left.isEmpty() ? right.pollFirst() : left.pollFirst();
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rebalance();
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return val;
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}
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public int popMiddle() {
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if (empty()) {
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return -1;
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}
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int val = left.size() >= right.size() ? left.pollLast() : right.pollFirst();
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rebalance();
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return val;
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}
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public int popBack() {
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if (empty()) {
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return -1;
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}
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int val = right.pollLast();
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rebalance();
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return val;
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}
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private boolean empty() {
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return left.isEmpty() && right.isEmpty();
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}
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private void rebalance() {
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while (left.size() > right.size()) {
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right.offerFirst(left.pollLast());
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}
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while (right.size() - left.size() > 1) {
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left.offerLast(right.pollFirst());
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}
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}
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}
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/**
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* Your FrontMiddleBackQueue object will be instantiated and called as such:
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* FrontMiddleBackQueue obj = new FrontMiddleBackQueue();
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* obj.pushFront(val);
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* obj.pushMiddle(val);
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* obj.pushBack(val);
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* int param_4 = obj.popFront();
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* int param_5 = obj.popMiddle();
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* int param_6 = obj.popBack();
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*/
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```
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### **...**

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