383. Ransom Note*

383. Ransom Note*

​​https://leetcode.com/problems/ransom-note/​​

题目描述

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

C++ 实现 1

使用哈希表.

class Solution {
public:
    bool canConstruct(string ransomNote, string magazine) {
        unordered_map<char, int> record;
        for (auto &c : magazine) record[c] ++;
        for (auto &c : ransomNote) {
            record[c] --;
            if (record[c] < 0) return false;
        }
        return true;
    }
};