leetcode:First Unique Character in a String

Given a string, find the first non-repeating character in it and return it’s index. If it doesn’t exist, return -1.

Examples:

s = “leetcode”

return 0.

s = “loveleetcode”,

return 2.

找出一个串里面第一个不重复的字母的下标

简单模拟题目

定义一个字母数组，用于保存该字母第一次出现的下标

如果该字母没有出现，为Integer.MAX_VALUE - 1

该字母出现了多次，定义为Integer.MAX_VALUE

然后找出最小的值

public class Solution {
public int firstUniqChar(String s) {
int[] vis = new int[26];
Arrays.fill(vis, Integer.MAX_VALUE - 1);
for(int i = 0; i < s.length(); ++i){
int index = s.charAt(i) - 'a';
if(vis[index] == Integer.MAX_VALUE)continue;
else if(vis[index] == Integer.MAX_VALUE - 1){
vis[index] = i;
}else{
vis[index] = Integer.MAX_VALUE;
}
}
int min = Integer.MAX_VALUE - 2;
for(int i : vis){
if(i < min)min = i;
}
return min == Integer.MAX_VALUE - 2 ? -1 : min;
}

}