Score: $250$ points

问题陈述

给定一个正整数序列 $A=(A_1,A_2,\dots,A_N)$，长度为 $N$，以及一个正整数 $K$。

找出在序列 $A$ 中不出现的、介于 $1$ 和 $K$（包括 $1$ 和 $K$）之间的整数的和。

以上为大语言模型 kimi 翻译，仅供参考。

Problem Statement

You are given a sequence of positive integers $A=(A_1,A_2,\dots,A_N)$ of length $N$ and a positive integer $K$.

Find the sum of the integers between $1$ and $K$, inclusive, that do not appear in the sequence $A$.

Constraints

• $1\leq N \leq 2\times 10^5$
• $1\leq K \leq 2\times 10^9$
• $1\leq A_i \leq 2\times 10^9$
• All input values are integers.

Input

The input is given from Standard Input in the following format:

$N$ $K$

$A_1$ $A_2$ $\dots$ $A_N$

Output

Print the answer.

Sample Input 1

4 5
1 6 3 1

Sample Output 1

11

Among the integers between $1$ and $5$, three numbers, $2$, $4$, and $5$, do not appear in $A$.

Thus, print their sum: $2+4+5=11$.

Sample Input 2

1 3
346

Sample Output 2

6

Sample Input 3

10 158260522
877914575 24979445 623690081 262703497 24979445 1822804784 1430302156 1161735902 923078537 1189330739

Sample Output 3

12523196466007058

update @ 2024/5/16 17:17:51