387.leetcode First Unique Character in a String(easy)[统计字符串字符次数]

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.

题目要找第一个没有重复的字符，那么首先扫描一遍string存放每个字符出现的次数，再对string扫描一遍，如果次数为1那么就返回其index

class Solution {
public:
int firstUniqChar(string s) {
//题目要找第一个没有重复的字符，那么首先扫描一遍string存放每个字符出现的次数，再对string扫描一遍，如果次数为1那么就返回其index
int n = s.length();
if(n<=0) return -1;
if(n == 1) return 0;
int sta[26];
memset(sta,0,sizeof(sta));
for(int i=0;i<n;i++)
sta[s[i]-'a']++;
for(int i=0;i<n;i++)
{
if(sta[s[i]-'a']==1)
return i;
}
return -1;
}
};