[剑指offer]第一个只出现一次的字符

题目描述

在一个字符串(0<=字符串长度<=10000，全部由字母组成)中找到第一个只出现一次的字符,并返回它的位置, 如果没有则返回 -1（需要区分大小写）.

 

 

题目链接：

https://www.nowcoder.com/practice/1c82e8cf713b4bbeb2a5b31cf5b0417c?tpId=13&tqId=11187&rp=2&ru=/ta/coding-interviews&qru=/ta/coding-interviews/question-ranking

 

 

 

 

 

package com.sunshine.OFFER66_SECOND;


import org.junit.Test;

import java.util.Map;
import java.util.TreeMap;

public class A34_FirstNotRepeatingChar {

    @Test
    public void test() {
        String str = "google";
        int a = FirstNotRepeatingChar(str);
        System.out.println(a);
    }


    public int FirstNotRepeatingChar(String str) {
        Map<Character, Integer> count = new TreeMap<>();
        char[] chars = str.toCharArray();
        for (char c : chars) {
            if (count.containsKey(c)) {
                Integer cc = count.get(c);
                count.put(c, cc + 1);
            } else {
                count.put(c, 1);
            }
        }
        for (int i = 0; i < chars.length; i++) {
            if (count.get(chars[i]) == 1) {
                return i;
            }
        }
        return -1;
    }
}