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

December LeetCoding Challenge 2

Description

Find Words That Can Be Formed by Characters

You are given an array of strings words and a string chars.

A string is good if it can be formed by characters from chars (each character can only be used once).

Return the sum of lengths of all good strings in words.

Example 1:

Input: words = ["cat","bt","hat","tree"], chars = "atach"
Output: 6
Explanation: The strings that can be formed are "cat" and "hat" so the answer is 3 + 3 = 6.

Example 2:

Input: words = ["hello","world","leetcode"], chars = "welldonehoneyr"
Output: 10
Explanation: The strings that can be formed are "hello" and "world" so the answer is 5 + 5 = 10.

Constraints:

• 1 <= words.length <= 1000
• 1 <= words[i].length, chars.length <= 100
• words[i] and chars consist of lowercase English letters.

Solution

class Solution {
public:
  int countCharacters(vector<string>& words, string chars) {
    vector<int> count(26);
    for(auto c : chars) {
      count[c - 'a'] += 1;
    }
    int answer = 0;
    for(const auto &word : words) {
      vector<int> ct(count);
      if(word.length() > chars.length()) continue;
      bool ok = true;
      for(auto c : word) {
        ct[c - 'a'] -= 1;
        if(ct[c - 'a'] < 0) ok = false;
      }
      if(ok) {
        answer += word.length();
      }
    }

    return answer;
  }
};

// Accepted
// 36/36 cases passed (44 ms)
// Your runtime beats 78.41 % of cpp submissions
// Your memory usage beats 71.98 % of cpp submissions (20.5 MB)