2014
02-24

# Pairs

Given n positive integers, is it possible to divide them into pairs so that the sum of each pair is the same?

The input contains several test cases. The first line of each case contains a single integer n (2 ≤ n ≤ 100). The second line contains n positive integers not greater than 1000. These numbers are sorted in non-decreasing order. The last case is followed by a single zero, which should not be processed.

The input contains several test cases. The first line of each case contains a single integer n (2 ≤ n ≤ 100). The second line contains n positive integers not greater than 1000. These numbers are sorted in non-decreasing order. The last case is followed by a single zero, which should not be processed.

4
1 3 4 6
3
1 1 1
0

Yes
No

//英语又没学好，题意是将n分成n/2份，判断n/2份都相等吗

#include<iostream>
using namespace std;
int a[1002];

int main()
{
int n, i, sum=0;
while(scanf("%d", &n) != EOF && n)
{
for( i=0; i < n; i++ )
scanf("%d", a+i);
int temp;
if(n % 2)
{
printf("No\n");
continue;
}
temp = a[0] + a[n-1];
for( i=1; i < n/2; i++ )
{
if(a[i] +a[n-i-1] != temp)	break;
}
if(i == n/2)
printf("Yes\n");
else
printf("No\n");
}
return 0;
}

1. 我没看懂题目
2
5 6 -1 5 4 -7
7 0 6 -1 1 -6 7 -5
我觉得第一个应该是5 6 -1 5 4 输出是19 5 4
第二个是7 0 6 -1 1 -6 7输出是14 7 7
不知道题目例子是怎么得出来的