2019-11-02 12:07:41 +08:00
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# 59. 滑动窗口的最大值
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[NowCoder](https://www.nowcoder.com/practice/1624bc35a45c42c0bc17d17fa0cba788?tpId=13&tqId=11217&tPage=1&rp=1&ru=/ta/coding-interviews&qru=/ta/coding-interviews/question-ranking&from=cyc_github)
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## 题目描述
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给定一个数组和滑动窗口的大小，找出所有滑动窗口里数值的最大值。
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例如，如果输入数组 {2, 3, 4, 2, 6, 2, 5, 1} 及滑动窗口的大小 3，那么一共存在 6 个滑动窗口，他们的最大值分别为 {4, 4, 6, 6, 6, 5}。
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## 解题思路
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```java
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public ArrayList<Integer> maxInWindows(int[] num, int size) {
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ArrayList<Integer> ret = new ArrayList<>();
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if (size > num.length || size < 1)
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return ret;
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PriorityQueue<Integer> heap = new PriorityQueue<>((o1, o2) -> o2 - o1); /* 大顶堆 */
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for (int i = 0; i < size; i++)
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heap.add(num[i]);
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ret.add(heap.peek());
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for (int i = 0, j = i + size; j < num.length; i++, j++) { /* 维护一个大小为 size 的大顶堆 */
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heap.remove(num[i]);
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heap.add(num[j]);
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ret.add(heap.peek());
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}
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return ret;
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}
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```
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2019-11-02 17:33:10 +08:00
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<div align="center"><img width="320px" src="https://cs-notes-1256109796.cos.ap-guangzhou.myqcloud.com/githubio/公众号二维码-2.png"></img></div>
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