Help me in solving MISSP problem

help
,
1

My issue

hey i got some 0rs instead of expected output but mostly the right output and i cant find the case where i get 0

My code

#include <stdio.h>

int nb_repetitons(int x, int y[100000], int num)
{
    int repetitions = 0;
    for (int i = 0; i <= x; i++){
        if (y[i] == num){
            repetitions++;
        }
    }
    return repetitions;
}

void solve(){
    int x, y[100000];
    scanf("%d", &x);
    for (int i = 0; i < x; i++){
        scanf("%d", &y[i]);
    }
    for (int i = 0; i <= x; i++){
        if (nb_repetitons(x, y, y[i]) % 2 != 0){
            printf("%d\n", y[i]);
            return;
        }
    }
    return;
}

int main(void) {
	int t;
	scanf("%d", &t);
	while (t--){
	    solve();
	}
	return 0;
}

Learning course: Arrays, Strings & Sorting
Problem Link: Chef and Dolls Practice Problem in - CodeChef

2

@inputname
logic is calculate the xor of the whole array.
the result will be the answer.