383. Ransom Note

383. Ransom Note (Easy)

Given an arbitrary ransom note string and another string containing letters from all the magazines, write a function that will return true if the ransom note can be constructed from the magazines ; otherwise, it will return false.

Each letter in the magazine string can only be used once in your ransom note.

Note:
You may assume that both strings contain only lowercase letters.

canConstruct("a", "b") -> false
canConstruct("aa", "ab") -> false
canConstruct("aa", "aab") -> true

Related Topics:
String

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Solution 1.

// OJ: https://leetcode.com/problems/ransom-note/
// Author: github.com/lzl124631x
// Time: O(M + N)
// Space: O(1)
class Solution {
public:
    bool canConstruct(string ransomNote, string magazine) {
        int cnt[26] = {0};
        for (char c : magazine) cnt[c - 'a']++;
        for (char c : ransomNote) {
            if (--cnt[c - 'a'] < 0) return false;
        }
        return true;
    }
};