Ransom Note

Leetcode Problem 383: Ransom Note

Problem Summary

Given two strings ransomNote and magazine, return true if the ransom note can be constructed using only characters from the magazine. Each character in the magazine can be used at most once.

Constraints:

• Both strings have between 1 and 100,000 characters, consisting of lowercase English letters only.

Techniques

• Hash Table
• String
• Counting

Solution

function canConstruct(ransomNote: string, magazine: string): boolean {
    const magazineLetterCount = new Map<string, number>()

    for(let i = 0; i < magazine.length; i++) {
        magazineLetterCount.set(magazine.charAt(i), (magazineLetterCount.get(magazine.charAt(i)) || 0) + 1)
    }

    for (let i = 0; i < ransomNote.length; i++) {
        if (!magazineLetterCount.has(ransomNote.charAt(i)) || magazineLetterCount.get(ransomNote.charAt(i)) === 0) {
            return false
        } else {
            magazineLetterCount.set(ransomNote.charAt(i), magazineLetterCount.get(ransomNote.charAt(i))! - 1)
        }
    }

    return true
};

console.log("aa", "aab")