2024-02-05 Daily Challenge

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Today I have done leetcode's February LeetCoding Challenge with cpp.

February LeetCoding Challenge 5

Description

First Unique Character in a String

Given a string s, find the first non-repeating character in it and return its index. If it does not exist, return -1.

 

Example 1:

Input: s = "leetcode"
Output: 0

Example 2:

Input: s = "loveleetcode"
Output: 2

Example 3:

Input: s = "aabb"
Output: -1

 

Constraints:

  • 1 <= s.length <= 105
  • s consists of only lowercase English letters.

Solution

class Solution {
public:
  int firstUniqChar(string s) {
    vector<int> pos(26, INT_MAX - 1);
    for(int i = 0; i < s.length(); ++i) {
      if(pos[s[i] - 'a'] == INT_MAX - 1) {
        pos[s[i] - 'a'] = i;
      } else {
        pos[s[i] - 'a'] = INT_MAX;
      }
    }
    int result = *min_element(pos.begin(), pos.end());
    return result > s.length() ? -1 : result;
  }
};

// Accepted
// 105/105 cases passed (15 ms)
// Your runtime beats 97.21 % of cpp submissions
// Your memory usage beats 24.32 % of cpp submissions (11.9 MB)
Algorithm