题解 | 出现奇数次的数

#include <stdio.h>

int main() {
	int n = 0;
	scanf("%d", &n);
	int first = 0;
	scanf("%d", &first);
	int each = 0;
	for (int i = 1;i < (2 * n + 1);i++) {
		scanf("%d", &each);
		first = first ^ each;
	}
	printf("%d", first);
	return 0;
}