<p>You are given an array of strings <code>words</code> and a string <code>chars</code>.</p>

<p>A string is <strong>good</strong> if it can be formed by characters from <code>chars</code> (each character can only be used once).</p>

<p>Return <em>the sum of lengths of all good strings in words</em>.</p>

<p>&nbsp;</p>
<p><strong class="example">Example 1:</strong></p>

<pre>
<strong>Input:</strong> words = [&quot;cat&quot;,&quot;bt&quot;,&quot;hat&quot;,&quot;tree&quot;], chars = &quot;atach&quot;
<strong>Output:</strong> 6
<strong>Explanation:</strong> The strings that can be formed are &quot;cat&quot; and &quot;hat&quot; so the answer is 3 + 3 = 6.
</pre>

<p><strong class="example">Example 2:</strong></p>

<pre>
<strong>Input:</strong> words = [&quot;hello&quot;,&quot;world&quot;,&quot;leetcode&quot;], chars = &quot;welldonehoneyr&quot;
<strong>Output:</strong> 10
<strong>Explanation:</strong> The strings that can be formed are &quot;hello&quot; and &quot;world&quot; so the answer is 5 + 5 = 10.
</pre>

<p>&nbsp;</p>
<p><strong>Constraints:</strong></p>

<ul>
	<li><code>1 &lt;= words.length &lt;= 1000</code></li>
	<li><code>1 &lt;= words[i].length, chars.length &lt;= 100</code></li>
	<li><code>words[i]</code> and <code>chars</code> consist of lowercase English letters.</li>
</ul>

#include <vector>
#include <cstring>
#include <map>

class Solution {
public:
    int countCharacters(vector<string>& words, string chars) 
    {
        map<char, int> count;
        int res = 0;

        // Count frequency of each character in `chars`
        for (int i = 0; chars[i] != '\0'; i++) 
        {
            count[chars[i]]++;
        }

        // Process each word in `words`
        for (int i = 0; i < words.size(); i++) 
        {
            map<char, int> cur_word;
            bool good = true;

            // Check if `words[i]` can be formed by `chars`
            for (int j = 0; words[i][j] != '\0'; j++) 
            {
                cur_word[words[i][j]]++;
                if (cur_word[words[i][j]] > count[words[i][j]]) 
                {
                    good = false;
                    break;
                }
            }

            // If the word is valid, add its length to the result
            if (good) 
            {
                res += words[i].length();
            }
        }

        return res;
    }

}
;
29688