#2206 - Divide Array Into Equal Pairs

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Array Hash Table Bit Manipulation Counting

Problem Description

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.

Solution

/**
 * @param {number[]} nums
 * @return {boolean}
 */
/**
 * @param {number[]} nums
 * @return {boolean}
 */
var divideArray = function(nums) {
  const map = new Map();

  for (const num of nums) {
    map.set(num, (map.get(num) || 0) + 1);
  }
  for (const count of map.values()) {
    if (count % 2 !== 0) {
      return false;
    }
  }

  return true;
};