33 lines
1.0 KiB
Java
33 lines
1.0 KiB
Java
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# 41.2 字符流中第一个不重复的字符
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[NowCoder](https://www.nowcoder.com/practice/00de97733b8e4f97a3fb5c680ee10720?tpId=13&tqId=11207&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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请实现一个函数用来找出字符流中第一个只出现一次的字符。例如，当从字符流中只读出前两个字符 "go" 时，第一个只出现一次的字符是 "g"。当从该字符流中读出前六个字符“google" 时，第一个只出现一次的字符是 "l"。
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## 解题思路
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```java
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private int[] cnts = new int[256];
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private Queue<Character> queue = new LinkedList<>();
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public void Insert(char ch) {
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cnts[ch]++;
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queue.add(ch);
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while (!queue.isEmpty() && cnts[queue.peek()] > 1)
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queue.poll();
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}
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public char FirstAppearingOnce() {
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return queue.isEmpty() ? '#' : queue.peek();
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}
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```
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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-1.png"></img></div>
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