README_EN.md

383. Ransom Note

中文文档

Description

Given two strings ransomNote and magazine, return true if ransomNote can be constructed from magazine and false otherwise.

Each letter in magazine can only be used once in ransomNote.

 

Example 1:

Input: ransomNote = "a", magazine = "b"
Output: false

Example 2:

Input: ransomNote = "aa", magazine = "ab"
Output: false

Example 3:

Input: ransomNote = "aa", magazine = "aab"
Output: true

 

Constraints:

• 1 <= ransomNote.length, magazine.length <= 105
• ransomNote and magazine consist of lowercase English letters.

Solutions

Python3

class Solution:
    def canConstruct(self, ransomNote: str, magazine: str) -> bool:
        counter = Counter(magazine)
        for c in ransomNote:
            if counter[c] <= 0:
                return False
            counter[c] -= 1
        return True

Java

class Solution {
    public boolean canConstruct(String ransomNote, String magazine) {
        int[] counter = new int[26];
        for (char c : magazine.toCharArray()) {
            ++counter[c - 'a'];
        }
        for (char c : ransomNote.toCharArray()) {
            if (counter[c - 'a'] <= 0) {
                return false;
            }
            --counter[c - 'a'];
        }
        return true;
    }
}

TypeScript

function canConstruct(ransomNote: string, magazine: string): boolean {
    let counter = new Array(26).fill(0);
    let base = 'a'.charCodeAt(0);
    for (let s of magazine) {
        ++counter[s.charCodeAt(0) - base];
    }
    for (let s of ransomNote) {
        let idx = s.charCodeAt(0) - base;
        if (counter[idx] == 0) return false;
        --counter[idx];
    }
    return true;
}

C++

class Solution {
public:
    bool canConstruct(string ransomNote, string magazine) {
        vector<int> counter(26);
        for (char c : magazine) ++counter[c - 'a'];
        for (char c : ransomNote)
        {
            if (counter[c - 'a'] <= 0) return false;
            --counter[c - 'a'];
        }
        return true;
    }
};

Go

func canConstruct(ransomNote string, magazine string) bool {
	rc := make([]int, 26)
	for _, b := range ransomNote {
		rc[b-'a']++
	}

	mc := make([]int, 26)
	for _, b := range magazine {
		mc[b-'a']++
	}

	for i := 0; i < 26; i++ {
		if rc[i] > mc[i] {
			return false
		}
	}
	return true
}

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