442. 数组中重复的数据🔖数组🔖哈希表

• https://leetcode-cn.com/problems/find-all-duplicates-in-an-array/

暴力解法

/**
 * @param {number[]} nums
 * @return {number[]}
 */
var findDuplicates = function (nums) {
  let arr = [];
  let result = [];
  nums.forEach((data) => {
    arr.includes(data) ? result.push(data) : arr.push(data);
  });
  return result;
};

哈希表

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

  for (let i = 0; i < nums.length; i++) {
    if (map.has(nums[i])) {
      arr.push(nums[i]);
      map.delete(nums[i]);
    } else {
      map.set(nums[i]);
    }
  }

  return arr;
};