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
};