Score : $200$ points

问题描述

给定一个包含 $N$ 个整数的序列 $A = (A_1, A_2, \dots, A_N)$，这些整数都在 $1$ 到 $N$（包括两端点）之间。

请判断序列 $A$ 是否为 $(1, 2, \dots, N)$ 的一个排列。

以上为通义千问 qwen-max 翻译，仅供参考。

Problem Statement

You are given a sequence of $N$ integers between $1$ and $N$ (inclusive): $A = (A_1, A_2, \dots, A_N)$.

Determine whether $A$ is a permutation of $(1, 2, \dots, N)$.

Constraints

• $1 \leq N \leq 10^3$
• $1 \leq A_i \leq N$
• All values in input are integers.

Input

Input is given from Standard Input in the following format:

$N$

$A_1$ $A_2$ $\ldots$ $A_N$

Output

If $A$ is a permutation of $(1, 2, \dots, N)$, print Yes; otherwise, print No.

Sample Input 1

5
3 1 2 4 5

Sample Output 1

Yes

$(3, 1, 2, 4, 5)$ is a permutation of $(1, 2, 3, 4, 5)$, so we should print Yes.

Sample Input 2

6
3 1 4 1 5 2

Sample Output 2

No

$(3, 1, 4, 1, 5, 2)$ is not a permutation of $(1, 2, 3, 4, 5, 6)$, so we should print No.

Sample Input 3

3
1 2 3

Sample Output 3

Yes

Sample Input 4

1
1

Sample Output 4

Yes

update @ 2024/3/10 09:18:08