Update 150 Java Version with SwitchCase #2937

Original file line number	Diff line number	Diff line change
Expand Up		@@ -162,6 +162,39 @@ class Solution {
		}
		```

	```Java
	// Switch Case 写法,更简洁一些
	class Solution {
	public int evalRPN(String[] tokens) {
	Stack<Integer> stk = new Stack<>();
	for (String token : tokens) {

	// 运算符Operator + - * /
	if ("+-*/".contains(token)) {
	int a = stk.pop(), b = stk.pop();
	switch (token) {
	case "+":
	stk.push(a + b);
	break;
	case "-":
	stk.push(b - a);
	break;
	case "*":
	stk.push(a * b);
	break;
	case "/":
	stk.push(b / a);
	break;
	}
	} else {
	stk.push(Integer.parseInt(token));
	}
	}
	return stk.pop();
	}
	}
	```

		### Python3:

		```python
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35 changes: 35 additions & 0 deletions problems/0239.滑动窗口最大值.md

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Original file line number	Diff line number	Diff line change
Expand Up		@@ -260,7 +260,9 @@ class Solution {
		return res;
		}
		}
	```

	```Java
		//解法二
		//利用双端队列手动实现单调队列
		/**
Expand Down Expand Up		@@ -296,6 +298,39 @@ class Solution {
		}
		```

	```Java
	//解法三
	//用优先队列 Priority Queue, 时间Time: O(nlogk) \| 空间Space: O(k)
	/**
	* 很好理解,PQ 会优先置顶最大值(Java Comparator)
	* 维护window里的 PQ, PQ内部记录 <value, index> pair
	**/
	class Solution {
	public int[] maxSlidingWindow(int[] nums, int k) {
	if (nums == null \|\| k <= 0)
	return new int[0];

	int n = nums.length;
	int[] res = new int[n - k + 1];
	PriorityQueue<int[]> maxHeap = new PriorityQueue<>((a, b) -> b[0] - a[0]);

	for (int i = 0; i < n; i++) {
	maxHeap.offer(new int[] { nums[i], i });

	// 删除窗口之外的元素
	while (maxHeap.peek()[1] <= i - k) {
	maxHeap.poll();
	}

	if (i >= k - 1) {
	res[i - k + 1] = maxHeap.peek()[0];
	}
	}
	return res;
	}
	}
	```

		### Python:
		#### 解法一:使用自定义的单调队列类
		```python
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43 changes: 43 additions & 0 deletions problems/0347.前K个高频元素.md

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Original file line number	Diff line number	Diff line change
Expand Up		@@ -213,6 +213,49 @@ class Solution {
		return res;
		}
		}
	```
	Java解法三:Bucket Sort 桶排序
	```java
	/**
	* 利用桶排序
	* 时间复杂度 O(n)
	* 空间复杂度 O(n)
	**/
	class Solution {
	public int[] topKFrequent(int[] nums, int k) {

	Map<Integer, Integer> freqMap = new HashMap<>();
	for (int num : nums) {
	freqMap.put(num, freqMap.getOrDefault(num, 0) + 1);
	}

	List<Integer>[] bucket = new List[nums.length + 1];
	for (int i = 0; i <= nums.length; i++) {
	bucket[i] = new ArrayList<>();
	}

	for (Map.Entry<Integer, Integer> entry : freqMap.entrySet()) {
	int num = entry.getKey();
	int freq = entry.getValue();
	bucket[freq].add(num);
	}

	List<Integer> result = new ArrayList<>();
	for (int i = bucket.length - 1; i >= 0 && result.size() < k; i--) {
	if (!bucket[i].isEmpty()) {
	result.addAll(bucket[i]);
	}
	}

	int[] res = new int[k];
	for (int i = 0; i < k; i++) {
	res[i] = result.get(i);
	}

	return res;
	}
	}

		```

		### Python:
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