order
This article mainly records leetcode The ransom letter
subject
Give a ransom (ransom) String and a magazine (magazine) character string , Judge the first string ransom Can I have a second string magazines The characters inside make up . If it can be constructed , return true ; Otherwise return to false.
( Title Description ： In order not to reveal the handwriting of the ransom letter , To search magazines for the letters you need , Make up words to express meaning . Each character in the magazine string can only be used once in the ransom letter string .)
Be careful ：
You can assume that both strings contain only lowercase letters .
canConstruct("a", "b") -> false
canConstruct("aa", "ab") -> false
canConstruct("aa", "aab") -> true
source ： Power button （LeetCode）
link ：https://leetcode-cn.com/problems/ransom-note
Copyright belongs to the network . For commercial reprint, please contact the official authority , Non-commercial reprint please indicate the source .Answer key
class Solution {
public boolean canConstruct(String ransomNote, String magazine) {
int[] charCount = new int[26];
for(char c : magazine.toCharArray()) {
charCount[c-'a'] += 1;
}
for(char c : ransomNote.toCharArray()) {
charCount[c-'a'] -= 1;
if (charCount[c-'a'] < 0) {
return false;
}
}
return true;
}
}Summary
Here we maintain an array of character occurrences , And then count it first magazine The number of occurrences of the character , And then I'm going through ransomNote, For each character that appears, the corresponding count is subtracted by one , Once the count is found to be less than 0 Then return to false, Otherwise, it will return after traversing true.
