hdoj-1563-Find your present!

Problem Description
In the new year party, everybody will get a “special present”.Now it’s your turn to get your special present, a lot of presents now putting on the desk, and only one of them will be yours.Each present has a card number on it, and your present’s card number will be the one that different from all the others.For example, there are 5 present, and their card numbers are 1, 2, 3, 2, 1.so your present will be the one with the card number of 3, because 3 is the number that different from all the others.

Input
The input file will consist of several cases.
Each case will be presented by an integer n (1<=n<=200, and n is odd) at first. Following that, n positive integers will be given in a line. These numbers indicate the card numbers of the presents.n = 0 ends the input.

Output
For each case, output an integer in a line, which is the card number of your present.

Sample Input
5
1 1 3 2 2
3
1 2 1
0

Sample Output
3
2

位运算xjb搞一下

#include <cstdio>#include <cstring>#include <algorithm>using namespace std;const int N = 200;int num[N], n, ans;int main(){    while (~scanf("%d", &n) && n)    {        for (int i=0; i<n; ++i) scanf("%d", &num[i]);        ans = num[0];        for (int i=1; i<n; ++i) ans ^= num[i];        printf("%d\n", ans);    }    return 0;}