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.
Note: You may assume the string contain only lowercase letters.

思路，统计每个每个字母出现的次数到一个数组中，数组大小为26个小写字母。

int firstUniqChar(char* s) {int i;char *str;int count[26];memset(count, 0, 26 * sizeof(int));for(str = s; *str != '\0'; str++) {i = *str - 'a';count[i]++;}for(str = s; *str != '\0'; str++) {i = *str - 'a';if(count[i] == 1)return str - s;}return -1;
}