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.

 

1 public class Solution { 2     public int FirstUniqChar(string s) { 3         var dict = new Dictionary
     

>(); 4 // Map 5 for (int i = 0; i < s.Length; i++) 6 { 7 if (!dict.ContainsKey(s[i])) 8 { 9 dict[s[i]] = new List

();10 }11 12 dict[s[i]].Add(i); 13 }14 　　　　　　 // Reduce15 bool found = false;16 var result = Int32.MaxValue;17 foreach (var pair in dict)18 {19 if (pair.Value.Count == 1 && pair.Value[0] < result)20 {21 found = true;22 result = pair.Value[0];23 }24 }25 26 return found ? result : -1;27 }28 }29 30 // traverse the string twice, if the string is super long, performance wouldn't be very good31 public class Solution1 {32 public int FirstUniqChar(string s) {33 var dict = new Dictionary

();34 35 foreach (var c in s)36 {37 if (!dict.ContainsKey(c))38 {39 dict[c] = 1;40 }41 else42 {43 dict[c]++;44 }45 }46 47 for (int i = 0; i < s.Length; i++)48 {49 if (dict[s[i]] == 1)50 {51 return i;52 }53 }54 55 return -1;56 }57 }