Question
Formatted question description: https://leetcode.ca/all/383.html
383 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
Algorithm
Hash Map counts the number of characters.
Code
Java
import java.util.HashMap;
import java.util.Map;
public class Ransom_Note {
class Solution {
public boolean canConstruct(String ransomNote, String magazine) {
if (ransomNote == null || magazine == null || ransomNote.length() > magazine.length()) {
return false;
}
int[] arr = new int[26];
for (int i = 0; i < magazine.length(); i++) {
arr[magazine.toLowerCase().charAt(i) - 'a']++;
}
for (int i = 0; i < ransomNote.length(); i++) {
if(--arr[ransomNote.toLowerCase().charAt(i)-'a'] < 0) {
return false;
}
}
return true;
}
}
class Solution_passed {
public boolean canConstruct(String ransomNote, String magazine) {
Map<Character, Integer> magM = new HashMap<>();
for (char c:magazine.toCharArray()){
int newCount = magM.getOrDefault(c, 0)+1;
magM.put(c, newCount);
}
for (char c:ransomNote.toCharArray()){
int newCount = magM.getOrDefault(c,0)-1;
if (newCount<0)
return false;
magM.put(c, newCount);
}
return true;
}
}
}