Submission #441587

#	Time	Username	Problem	Language	Result	Execution time	Memory
441587		rainboy	Islands (IOI08_islands)	C11	27 / 100	287 ms	43032 KiB

islands

#include <stdio.h>

#define N	1000000
#define INF	0x3f3f3f3f3f3f3f3f

long long max(long long a, long long b) { return a > b ? a : b; }

int main() {
	static int pp[N], ww[N], in[N];
	static long long dd1[N], dd2[N];
	int n, i, j;
	long long ans;

	scanf("%d", &n);
	for (i = 0; i < n; i++) {
		scanf("%d%d", &pp[i], &ww[i]), pp[i]--;
		in[pp[i]]++;
	}
	for (i = 0; i < n; i++)
		for (j = i; in[j] == 0; j = pp[j]) {
			int p = pp[j];

			dd2[p] = max(max(dd2[p], dd2[j]), dd1[p] + dd1[j] + ww[j]);
			dd1[p] = max(dd1[p], dd1[j] + ww[j]);
			in[p]--;
		}
	ans = 0;
	for (i = 0; i < n; i++)
		if (in[i] != 0) {
			long long d, e, f, w, x, y;

			d = e = f = -INF, w = 0, x = y = -INF, j = i;
			for (j = i; in[j] != 0; j = pp[j]) {
				in[j] = 0;
				d = max(d, dd2[j]);
				if (x != -INF)
					e = max(e, x + dd1[j]);
				if (y != -INF)
					f = max(f, y + dd1[j]);
				w += ww[j], x = max(x, dd1[j]) + ww[j], y = max(y, dd1[j]) - ww[j];
			}
			ans += max(d, max(e, f + w));
		}
	printf("%lld\n", ans);
	return 0;
}

Compilation message (stderr)

islands.c: In function 'main':
islands.c:14:2: warning: ignoring return value of 'scanf' declared with attribute 'warn_unused_result' [-Wunused-result]
   14 |  scanf("%d", &n);
      |  ^~~~~~~~~~~~~~~
islands.c:16:3: warning: ignoring return value of 'scanf' declared with attribute 'warn_unused_result' [-Wunused-result]
   16 |   scanf("%d%d", &pp[i], &ww[i]), pp[i]--;
      |   ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 27 / 33
• Subtask 2: 0 / 3
• Subtask 3: 0 / 4
• Subtask 4: 0 / 10
• Subtask 5: 0 / 10
• Subtask 6: 0 / 10
• Subtask 7: 0 / 10
• Subtask 8: 0 / 10
• Subtask 9: 0 / 10