数据结构——Currency System in Geraldion

最新推荐文章于 2025-08-15 16:44:13 发布

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最新推荐文章于 2025-08-15 16:44:13 发布

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文章标签：数据结构与算法

原文链接：http://www.cnblogs.com/www-cnxcy-com/p/4675925.html

本文介绍了一个算法问题，探讨如何找出一种货币系统中无法用现有纸币面额组合而成的最小金额。若存在面额为1的纸币，则所有金额均可被组合，此时问题无解，输出-1；反之，最小不幸金额即为1。

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题目：

Description

A magic island Geraldion, where Gerald lives, has its own currency system. It uses banknotes of several values. But the problem is, the system is not perfect and sometimes it happens that Geraldionians cannot express a certain sum of money with any set of banknotes. Of course, they can use any number of banknotes of each value. Such sum is called unfortunate. Gerald wondered: what is the minimum unfortunate sum?

Input

The first line contains number n (1 ≤ n ≤ 1000) — the number of values of the banknotes that used in Geraldion.

The second line contains n distinct space-separated numbers a₁, a₂, ..., a_n (1 ≤ a_i ≤ 10⁶) — the values of the banknotes.

Output

Print a single line — the minimum unfortunate sum. If there are no unfortunate sums, print - 1.

Sample Input

Input

5
1 2 3 4 5

Output

-1

解题思路：

题目意思就是判断输入的N 个数里面是否有1，若有，则输出-1，没有则输出1

程序代码：

#include <iostream>
#include <cstdio>
using namespace std;
int a[1005];
int main()
{
    int n,f=0;
    cin>>n;
    for(int i=0;i<n;i++)
      {
           scanf("%d",&a[i]);
           if(a[i]==1)  f=1;
      }

    if(f==1)    cout<<-1<<"\n";
    else cout<<1<<"\n";
    return 0;

}