题解 | 小红的不动点分配

#include <stdio.h>

int main() {
	int n = 0;
    scanf("%d", &n);
	int arr[2 * 199990] = {0};
	int num = 0;
	int times = 0;
	for (int i = 0; i < 2*n; i++) {
		scanf("%d", &num);
		if (num <= n) {
			arr[num]++;
		}
	}
	for (int i = 0; i <= n; i++) {
		if (arr[i] == 1) {
			times++;
		}
		else if (arr[i] >= 2) {
			times += 2;
		}
	}
	printf("%d", times);
	return 0;
}