leetcode-0387 字符串中的第一个唯一字符

[GuoLizhi]

题目地址 https://leetcode-cn.com/problems/first-unique-character-in-a-string/

Hash Table

时间复杂度O(n) 空间复杂度O(n)

var firstUniqChar = function(s) {
    let map = {};
    for (let i = 0; i < s.length; i++) {
        const c = s[i];
        map[c] = map[c] !== undefined ? map[c] + 1 : 1;
    }
    for (let i = 0; i < s.length; i++) {
        if (map[s[i]] === 1)
            return i;
    }
    return -1;
};