LeetCode Ransom Note (Java)
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.
|
1 2 3 4 |
canConstruct("a", "b") -> false canConstruct("aa", "ab") -> false canConstruct("aa", "aab") -> true |
Java Solution
|
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 |
public class Solution { public boolean canConstruct(String ransomNote, String magazine) { // if(ransomNote == null && magazine == null) return true; // if(ransomNote == null) return true; // if(magazine == null) return false; // if(ransomNote.length() == 0 && magazine.length() == 0) return true; // if(ransomNote.length() > magazine.length()) return false; Map<Character, Integer> freq = new HashMap<>(); for(char c: magazine.toCharArray()) { if(freq.containsKey(c)) { freq.put(c, freq.get(c) + 1); } else { freq.put(c, 1); } } for(char c: ransomNote.toCharArray()) { if (freq.containsKey(c)) { if(freq.get(c) > 1) { freq.put(c, freq.get(c) - 1); } else { freq.remove(c); } }else{ return false; } } return true; } } |
