2019-11-02 12:07:41 +08:00
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# 31. 栈的压入、弹出序列
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2020-11-04 01:44:39 +08:00
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## 题目链接
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[牛客网](https://www.nowcoder.com/practice/d77d11405cc7470d82554cb392585106?tpId=13&tqId=11174&tPage=1&rp=1&ru=/ta/coding-interviews&qru=/ta/coding-interviews/question-ranking&from=cyc_github)
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2019-11-02 12:07:41 +08:00
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## 题目描述
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输入两个整数序列，第一个序列表示栈的压入顺序，请判断第二个序列是否为该栈的弹出顺序。假设压入栈的所有数字均不相等。
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例如序列 1,2,3,4,5 是某栈的压入顺序，序列 4,5,3,2,1 是该压栈序列对应的一个弹出序列，但 4,3,5,1,2 就不可能是该压栈序列的弹出序列。
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## 解题思路
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2020-11-04 01:44:39 +08:00
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使用一个栈来模拟压入弹出操作。每次入栈一个元素后，都要判断一下栈顶元素是不是当前出栈序列 popSequence 的第一个元素，如果是的话则执行出栈操作并将 popSequence 往后移一位，继续进行判断。
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2019-11-02 12:07:41 +08:00
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```java
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public boolean IsPopOrder(int[] pushSequence, int[] popSequence) {
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int n = pushSequence.length;
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Stack<Integer> stack = new Stack<>();
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for (int pushIndex = 0, popIndex = 0; pushIndex < n; pushIndex++) {
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stack.push(pushSequence[pushIndex]);
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while (popIndex < n && !stack.isEmpty()
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&& stack.peek() == popSequence[popIndex]) {
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stack.pop();
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popIndex++;
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}
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}
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return stack.isEmpty();
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}
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```
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2019-11-02 14:39:13 +08:00
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2020-11-04 01:44:39 +08:00
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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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