Maximum size of a set after removals

Array Hash Table Greedy

46.1% acceptance

Feb 25, 2026

323

You are given two 0-indexed integer arrays nums1 and nums2 of even length n. You must remove n / 2 elements from nums1 and n / 2 elements from nums2. After the removals, you insert the remaining elements of nums1 and nums2 into a set s. Return the maximum possible size of the set s.

Solution

Rust

Time O(n)

Space O(1)

LeetCode

solution.rs

impl Solution {
  pub fn maximum_set_size(nums1: Vec<i32>, nums2: Vec<i32>) -> i32 {
    use std::collections::HashSet;
    let n = nums1.len();
    let half = n / 2;
    let set1: HashSet<i32> = nums1.into_iter().collect();
    let set2: HashSet<i32> = nums2.into_iter().collect();
    let common = set1.intersection(&set2).count();
    let only1 = set1.len() - common;
    let only2 = set2.len() - common;
    let k1 = only1.min(half);
    let k2 = only2.min(half);
    let common_kept = common.min((half - k1) + (half - k2));
    (k1 + k2 + common_kept) as i32
  }
}