1160. 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 for each word in words).

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.

From: LeetCode
Link: 1160. Find Words That Can Be Formed by Characters

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Solution:

Ideas:

• count available letters in chars, then check whether each word’s letter counts exceed them.

Code:

int countCharacters(char** words, int wordsSize, char* chars) {
    int base[26] = {0};
    int ans = 0;

    for (int i = 0; chars[i] != '\0'; i++) {
        base[chars[i] - 'a']++;
    }

    for (int i = 0; i < wordsSize; i++) {
        int cnt[26] = {0};
        int len = 0;
        int good = 1;

        for (int j = 0; words[i][j] != '\0'; j++) {
            int idx = words[i][j] - 'a';
            cnt[idx]++;
            len++;

            if (cnt[idx] > base[idx]) {
                good = 0;
                break;
            }
        }

        if (good) {
            ans += len;
        }
    }

    return ans;
}