# 448. Find All Numbers Disappeared in an Array ###### tags: `hash table` https://leetcode.com/problems/find-all-numbers-disappeared-in-an-array/ ![](https://i.imgur.com/3gHPvk4.png) ## 思路: 1. 一樣建立hash table把這個list 出現過的element 當成key 然後重複出現當成value 2. hash table 不能用set 替代,因為有累積數字問題,set 只能達到hash table 的key 3.