Leetcode: Ransom Note

Ransom Note



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

Github: code.dennyzhang.com

Credits To: leetcode.com

Leave me comments, if you have better ways to solve.


## Blog link: https://code.dennyzhang.com/ransom-note
class Solution(object):
    def canConstruct(self, ransomNote, magazine):
        """
        :type ransomNote: str
        :type magazine: str
        :rtype: bool
        """
        ## Idea: 2 dict
        ## Complexity: Time O(n), Space O(n)
        lower_letters = map(chr, range(ord('a'), ord('z')+1))
        r_dict = {}
        m_dict = {}
        for ch in lower_letters:
            r_dict[ch] = 0
            m_dict[ch] = 0

        for ch in ransomNote:
            r_dict[ch] += 1

        for ch in magazine:
            m_dict[ch] += 1

        for ch in lower_letters:
            if m_dict[ch] - r_dict[ch] < 0:
                return False
        return True
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