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

题意：从这一列数中找到一个只出现了一次的数。只找一个就够了。

#include<stdio.h> #include<string.h> #define max 10000000 short a[max]; int main() { int i,n,j; while(~scanf("%d",&n)&&n) { memset(a,0,sizeof(a)); for(i=0;i<n;i++) { scanf("%d",&j); a[j]++; } for(i=0;i<max;i++) { if(a[i]==1) { printf("%d\n",i); break; } } } return 0; }