LeetCode in TypeScript

383. Ransom Note

Easy

Given two stings 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.

Solution

function canConstruct(ransomNote: string, magazine: string): boolean {
    const freq: number[] = new Array(26).fill(0)
    let remaining = ransomNote.length
    for (let i = 0; i < remaining; i++) {
        freq[ransomNote.charCodeAt(i) - 97]++
    }
    for (let i = 0; i < magazine.length && remaining > 0; i++) {
        const index = magazine.charCodeAt(i) - 97
        if (freq[index] > 0) {
            freq[index]--
            remaining--
        }
    }
    return remaining === 0
}

export { canConstruct }

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