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.
Example 1:
Input: ransomNote = "a", magazine = "b"
Output: false
Example 2:
Input: ransomNote = "aa", magazine = "ab"
Output: false
Example 3:
Input: ransomNote = "aa", magazine = "aab"
Output: true
Constraints:
- You may assume that both strings contain only lowercase letters.
Solution
这个题的思路就是看看ransomNote中的每个字符是不是都在magazine 中，重复的也要考虑，我们借助python的Counter，把ransomNote和magazine 都转化成Counter，然后比较ransomNote中每个字符对应的计数器是不是都大于magazine ，如果是，则返回true，否则返回false。
from collections import Counter
class Solution:
def canConstruct(self, ransomNote: str, magazine: str) -> bool:
rans = Counter(ransomNote)
mags = Counter(magazine)
for s in rans:
if mags[s]<rans[s]:
return False
return True
