Ransom note

Hash Table String Counting

65.7% acceptance

Jan 12, 2026

5641

543

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

Solution

Rust

Time O(n)

Space O(1)

LeetCode

solution.rs

impl Solution {
  pub fn can_construct(ransom_note: String, magazine: String) -> bool {
    let mut counts = [0; 26];
    
    for b in magazine.bytes() {
      counts[(b - b'a') as usize] += 1;
    }
    
    for b in ransom_note.bytes() {
      let idx = (b - b'a') as usize;
      if counts[idx] == 0 {
        return false;
      }
      counts[idx] -= 1;
    }
    
    true
  }
}