383. 赎金信

题目描述

 给定一个赎金信 (ransom) 字符串和一个杂志(magazine)字符串，判断第一个字符串 ransom 能不能由第二个字符串 magazines 里面的字符构成。如果可以构成，返回 true ；否则返回 false。

 (题目说明：为了不暴露赎金信字迹，要从杂志上搜索各个需要的字母，组成单词来表达意思。杂志字符串中的每个字符只能在赎金信字符串中使用一次。)

原题请参考链接https://leetcode-cn.com/problems/ransom-note/

题解

方法一 【哈希表(哈希Map)】

class Solution:
    def canConstruct(self, ransomNote: str, magazine: str) -> bool:
        count_dic = dict()
        for i in magazine:
            if i in count_dic:
                count_dic[i] += 1
            else:
                count_dic[i] = 1
        for i in ransomNote:
            if i in count_dic:
                if count_dic[i] <= 0:
                    return False
                count_dic[i] -= 1
            else:
                return False
        return True

方法二 【哈希表(哈希数组)】

class Solution:
    def canConstruct(self, ransomNote: str, magazine: str) -> bool:
        l = [0] *26
        for i in magazine:
            l[ord(i)-ord('a')] += 1
        for i in ransomNote:
            if l[ord(i)-ord('a')] == 0:
                return False
            l[ord(i)-ord('a')] -= 1
                
        return True