算法:第一个只出现一次的字符位置

public class Solution {
    public int FirstNotRepeatingChar(String str) {
        int[] map = new int[256];
        int len = str.length();
        for (int i = 0; i < len; ++i) {
            map[str.charAt(i)]++;
        }
        for (int i = 0; i < len; ++i) {
            if (map[str.charAt(i)] == 1) return i;
        }
        return -1;
    }
}