题目

Given an array of integers where 1 ≤ a[i] ≤ n (n = size of array), some elements appear twice and others appear once.

Find all the elements of [1, n] inclusive that do not appear in this array.

Could you do it without extra space and in O(n) runtime? You may assume the returned list does not count as extra space.

Example:

Input:[4,3,2,7,8,2,3,1]Output:[5,6]复制代码

to see which companies asked this question.

代码

func findDisappearedNumbers(_ nums: [Int]) -> [Int] {    var tmp = nums;    var arr: [Int] = []    for i in 0..
    
      0 {            tmp[index] *= -1        }    }    for i in 0..
     
       0 {            arr.append(i+1)        }    }    return arr;}复制代码