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

Solution

public class Solution {
    public boolean canConstruct(String ransomNote, String magazine) {
        if (ransomNote == null || magazine == null) return false;

        int[] array1 = new int[26];
        int[] array2 = new int[26];

        for (char c : ransomNote.toCharArray()) {
            array1[c - 'a'] += 1;
        }

        for (char c : magazine.toCharArray()) {
            array2[c - 'a'] += 1;
        }

        for (int i = 0; i < 26; i++) {
            if (array2[i] < array1[i]) {
                return false;
            }
        }

        return true;
    }
}