LeetCode #: 383
Difficulty: Easy
Topic: String.
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
Assume m is the length of magazine string and n is the ransomNote string.
Time complexity: O(m+n). In worst case scenario, we will loop through every character in magazine and ransomNote once.
Space complexity: O(1). We use an array of maximum 26 elements to store the count of characters in magazine.