Leetcode 387. First Unique Character in a String

文章作者：Tyan
博客：noahsnail.com  |  CSDN  |  简书

1. Description

2. Solution

• Two loops

class Solution {
public:
    int firstUniqChar(string s) {
        int index[256] = {0};
        for(int i = 0; i < s.size(); i++) {
            index[s[i]]++;
        }
        for(int i = 0; i < s.size(); i++) {
            if(index[s[i]] == 1) {
                return i;
            }
        }
        return -1;
    }
};

• Nested loop

  class Solution {
  public:
      int firstUniqChar(string s) {
          int index[256] = {0};
          for(int i = 0; i < s.size(); i++) {
              index[s[i]]++;
              if(index[s[i]] != 1) {
                  continue;
              }
              bool flag = false;
              for(int j = i + 1; j < s.size(); j++) {
                  if(s[i] == s[j]) {
                      flag = true;
                      break;
                  }
              }
              if(!flag) {
                  return i;
              }
          }
          return -1;
      }
  };

Reference

1. https://leetcode.com/problems/first-unique-character-in-a-string/description/