README.md

2206. Divide Array Into Equal Pairs

You are given an integer array nums consisting of 2 * n integers.

You need to divide nums into n pairs such that:

• Each element belongs to exactly one pair.
• The elements present in a pair are equal.

Return true if nums can be divided into n pairs, otherwise return false.

Example 1:

Input: nums = [3,2,3,2,2,2]
Output: true
Explanation:
There are 6 elements in nums, so they should be divided into 6 / 2 = 3 pairs.
If nums is divided into the pairs (2, 2), (3, 3), and (2, 2), it will satisfy all the conditions.

Example 2:

Input: nums = [1,2,3,4]
Output: false
Explanation:
There is no way to divide nums into 4 / 2 = 2 pairs such that the pairs satisfy every condition.

Constraints:

• nums.length == 2 * n
• 1 <= n <= 500
• 1 <= nums[i] <= 500

Solutions (Rust)

1. Solution

use std::collections::HashMap;

impl Solution {
    pub fn divide_array(nums: Vec<i32>) -> bool {
        let mut count = HashMap::new();

        for num in nums {
            *count.entry(num).or_insert(0) += 1;
        }

        count.values().all(|v| v % 2 == 0)
    }
}