Leetcode 2195. Append K Integers With Minimal Sum

You are given an integer array nums and an integer k. Append k unique positive integers that do not appear in nums to nums such that the resulting total sum is minimum.

Return the sum of the k integers appended to nums.

Example 1:

Input: nums = [1,4,25,10,25], k = 2Output: 5Explanation: The two unique positive integers that do not appear in nums which we append are 2 and 3. The resulting sum of nums is 1 + 4 + 25 + 10 + 25 + 2 + 3 = 70, which is the minimum. The sum of the two integers appended is 2 + 3 = 5, so we return 5.

Example 2:

Input: nums = [5,6], k = 6Output: 25Explanation: The six unique positive integers that do not appear in nums which we append are 1, 2, 3, 4, 7, and 8. The resulting sum of nums is 5 + 6 + 1 + 2 + 3 + 4 + 7 + 8 = 36, which is the minimum. The sum of the six integers appended is 1 + 2 + 3 + 4 + 7 + 8 = 25, so we return 25.

Constraints:

• 1 <= nums.length <= 10(5)

• 1 <= nums[i] <= 10(9)

• 1 <= k <= 10(8)

第一个方法就是常规思路，但是TLE(TIME LIMIT EXCEED)超时了，

所以 只能转换思路，因为K会很大，为了减少遍历k内部的数字，于是先把k以内的数字求和，

然后去判断数字在数组中是否存在（为了方便，把数组放在set-集合中），如果存在了，则sum-i, cnt++（这里cnt就要去用大于k的数字去添加了）。

遍历后再去根据cnt的大小去遍历大于k的数字，这时候还是要判断在不在set中，

遍历完就可以return了。

Runtime: 37 ms, faster than 60.47% of Java online submissions for Append K Integers With Minimal Sum.

Memory Usage: 59.2 MB, less than 75.35% of Java online submissions for Append K Integers With Minimal Sum.