View Code of Problem 3929

#include<stdio.h>
#include<math.h>
struct  num{
	int data;
	int c;
	int flag;
};
int main(){
	int t,i,j;
	scanf("%d",&t);
	while(t--){
		int n;
		scanf("%d",&n);
		struct num a[n];
		for(i=0;i<n;i++){
		scanf("%d",&a[i].data);
	      a[i].c=1;
	      a[i].flag=0;
	}
		for(i=0;i<n;i++){
			if(a[i].flag==0){
			for(j=i+1;j<n;j++){
				if(a[i].data==a[j].data)
				{
				a[i].c++;
			    a[j].flag=1;
			}
			}
		}
		else
		a[i].c=2;
	}
	int b[n],k=0;
	for(i=0;i<n;i++){
		if(a[i].c%2!=0)
		b[k++]=a[i].data;
	}
	int s=b[0];
	for(i=1;i<k;i++)
	s^=b[i];
	printf("%d\n",s);
}
}