Check if any element has prime frequency

Array Hash Table Math Counting Number Theory

62.5% acceptance

Feb 25, 2026

You are given an integer array nums. Return true if the frequency of any element of the array is prime, otherwise return false.

Solution

Rust

Time O(n)

Space O(n)

LeetCode

solution.rs

impl Solution {
  pub fn check_prime_frequency(nums: Vec<i32>) -> bool {
    let mut freq = std::collections::HashMap::new();
    for &x in &nums {
      *freq.entry(x).or_insert(0usize) += 1;
    }
    let is_prime = |n: usize| -> bool {
      if n < 2 { return false; }
      if n == 2 { return true; }
      if n % 2 == 0 { return false; }
      let mut i = 3;
      while i * i <= n {
        if n % i == 0 { return false; }
        i += 2;
      }
      true
    };
    freq.values().any(|&f| is_prime(f))
  }
}