#1338 - Reduce Array Size to The Half

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Array Hash Table Sorting Greedy Heap Priority Queue

Problem Description

You are given an integer array arr. You can choose a set of integers and remove all the occurrences of these integers in the array.

Return the minimum size of the set so that at least half of the integers of the array are removed.

Solution

/**
 * @param {number[]} arr
 * @return {number}
 */
var minSetSize = function(arr) {
  const map = new Map();
  const halfLength = arr.length / 2;

  arr.forEach(num => map.set(num, (map.get(num) || 0) + 1));

  const frequencies = Array.from(map.values()).sort((a, b) => b - a);

  let removedCount = 0;
  let result = 0;

  for (const freq of frequencies) {
    removedCount += freq;
    result++;
    if (removedCount >= halfLength) break;
  }

  return result;
};