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  1. #include<stdio.h>
  2. int is_gone[121212], ck[121212], a[121212];
  3. int main() {
  4. 	int n, i, t = 1, ans = 0;
  5. 	scanf("%d", &n);
  6. 	for (i = 1; i <= n; i++)scanf("%d", &a[i]);
  7. 	for (i = 1; i <= n; i++) {
  8. 		if (is_gone[i])continue;
  9. 		int now = i;
  10. 		while (1) {
  11. 			ck[now] = i, is_gone[now] = t++;
  12. 			if (ck[a[now]] != 0) {
  13. 				if (ck[a[now]] == i) ans += t - is_gone[a[now]];
  14. 				break;
  15. 			}
  16. 			now = a[now];
  17. 		}
  18. 	}
  19. 	printf("%d", ans);
  20. 	return 0;
  21. }
Success #stdin #stdout 0s 4376KB
comments (?)
stdin 
4
3 2 1 3
stdout 
3
https://ideone.com/5wMV6X
language:
C++14 (gcc 8.3)
created:
6 years ago
visibility:
secret

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