Overview

Given two strings ransomNote and magazine, return true if ransomNote can be constructed using the letters from magazine. Each letter in magazine can only be used once.

Constraints

• 1 <= ransomNote.length, magazine.length <= 100,000
• Both consist of lowercase English letters.

Examples

canConstruct("a", "b");     // => false
canConstruct("aa", "ab");   // => false
canConstruct("aa", "aab");  // => true

Solution

function canConstruct(ransomNote, magazine) {
  const freq = {};
  for (const c of magazine) freq[c] = (freq[c] || 0) + 1;
  for (const c of ransomNote) {
    if (!freq[c]) return false;
    freq[c]--;
  }
  return true;
}

Resources

• Ransom Note — LeetCode