Stick

Description:

Anthony has collected a large amount of sticks for manufacturing chopsticks. In order to

simplify his job, he wants to fetch two equal-length sticks for machining at a time. After checking

it over, Anthony finds that it is always possible that only one stick is left at last, because of the odd

number of sticks and some other unknown reasons. For example, Anthony may have three sticks

with length 1, 2, and 1 respectively. He fetches the first and the third for machining, and leaves the

second one at last. You task is to report the length of the last stick.

Input:

The input file will consist of several cases.

Each case will be presented by an integer n (1<=n<=100, and n is odd) at first. Following that,

n positive integers will be given, one in a line. These numbers indicate the length of the sticks

collected byAnthony.

The input is ended by n=0.

Output:

For each case, output an integer in a line, which is the length of the last stick.

Sample Input:

3
1
2
1
0

Sample Output:

2


一开始想过很多方法都没过，看了别人的代码才发现位运算这个奇妙的东西，如今已将此题列为“水题”。
不得不感叹，位运算好奇妙。。。



#include<cstdio>
#include<cstring>
#include<algorithm>
#define maxn 100010
using namespace std;
int main()
{
    int ans,a[110],n;
    while(scanf("%d",&n)==1&&n)
    {
        scanf("%d",&a[0]);
        ans=a[0];
        for(int i=1;i<n;i++)
        {
            scanf("%d",&a[i]);
            ans^=a[i];
        }
        printf("%d\n",ans);
    }
    return 0;
}