题目

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

难度

Easy

方法

遍历2个字符串，索引分别为i, j，如果ransomNote[i] == magazine[j]，则i++, j++，否则j++。如果i == len(ransomNote)，则表示能够用magazine的字符组成ransomNote，否则则不能

python代码

class Solution(object):
    def canConstruct(self, ransomNote, magazine):
        ransomNote = sorted(ransomNote)
        magazine = sorted(magazine)

        i = 0
        j = 0
        while i < len(ransomNote) and j < len(magazine):
            if ransomNote[i] == magazine[j]:
                j += 1
                i += 1
            else:
                j += 1
   
        if i == len(ransomNote):
            return True
        return False

assert Solution().canConstruct("a", "b") == False
assert Solution().canConstruct("aa", "ab") == False
assert Solution().canConstruct("aa", "aab") == True
assert Solution().canConstruct("djfjfhjf", "aaigcbiafifghhdihcfdjjej") == True