1160. Find Words That Can Be Formed by Characters

package LeetCode_1160

/**
 * 1160. Find Words That Can Be Formed by Characters
 * https://leetcode.com/problems/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.

Note:
1. 1 <= words.length <= 1000
2. 1 <= words[i].length, chars.length <= 100
3. All strings contain lowercase English letters only.
 * */
class Solution {
    /*
    * solution: Array, keep tracking if letter match,
    * Time:O(m*n), Space:O(1), m: size of words, n: longest length of word
    * */
    fun countCharacters(words: Array<String>, chars: String): Int {
        var result = 0
        //just handling lowercase
        val map = IntArray(26)
        for (c in chars) {
            map[c - 'a']++
        }
        for (word in words) {
            val map2 = map.clone()
            //current word's length
            var curLength = 0
            for (c in word) {
                //if match one character,curLength++
                if (map2[c - 'a'] > 0) {
                    map2[c - 'a']--
                    curLength++
                }
            }
            if (curLength == word.length) {
                result += curLength
            }
        }
        return result
    }
}