共计 683 个字符，预计需要花费 2 分钟才能阅读完成。
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.
难度: easy
题目：给定字符串，找出第一个不重复的字符，并返回其下标。如果不存在则返回-1.
思路：数组分别记录下标与出现次数。
Runtime: 10 ms, faster than 93.94% of Java online submissions for First Unique Character in a String.Memory Usage: 40 MB, less than 14.74% of Java online submissions for First Unique Character in a String.
class Solution {
public int firstUniqChar(String s) {
int[] count = new int[26];
int[] index = new int[26];
int result = s.length();
for (int i = 0; i < result; i++) {
char c = s.charAt(i);
count++;
index = i + 1;
}
for (int i = 0; i < 26; i++) {
if (1 == count[i]) {
result = Math.min(result, index[i] – 1);
}
}
return result >= s.length() ? -1 : result;
}
}
