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.
思路：利用ascii建array。扫两遍string，第一遍记录每个char的次数，扫第二遍string，碰到次数为1的直接输出。
public class Solution { public int firstUniqChar(String s) { if(s.length()==0) { return -1; } int[] res=new int[128]; for(int i=0;i<s.length();i++) { if(res[s.charAt(i)]==0) { res[s.charAt(i)]=1; } else { res[s.charAt(i)]++; } } for(int i=0;i<s.length();i++) { if(res[s.charAt(i)]==1) { return i; } } return -1; } }
387. First Unique Character in a String
原文：http://www.cnblogs.com/Machelsky/p/5944450.html