HDU 1563 Find your present!

Find your present!

[align=left]Problem Description[/align]
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.
 

[align=left]Input[/align]
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.
 
[align=left]Output[/align]
For each case, output an integer in a line, which is the card number of your present.
 
[align=left]Sample Input[/align]

5
1 1 3 2 2
3
1 2 1
0

 
[align=left]Sample Output[/align]

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;
}