Submission #503267

#	Time	Username	Problem	Language	Result	Execution time	Memory
503267		rainboy	Magneti (COCI21_magneti)	C11	110 / 110	42 ms	4380 KiB

Main

#include <stdio.h>
#include <string.h>

#define N	50
#define L	10000
#define MD	1000000007

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

unsigned int X;

int rand_() {
	return (X *= 3) >> 1;
}

int vv[L + 1], ff[L + 1], gg[L + 1];

void init() {
	int i;

	ff[0] = gg[0] = 1;
	for (i = 1; i <= L; i++) {
		vv[i] = i == 1 ? 1 : (long long) vv[i - MD % i] * (MD / i + 1) % MD;
		ff[i] = (long long) ff[i - 1] * i % MD;
		gg[i] = (long long) gg[i - 1] * vv[i] % MD;
	}
}

int choose(int n, int k) {
	return k < 0 || k > n ? 0 : (long long) ff[n] * gg[k] % MD * gg[n - k] % MD;
}

void sort(int *aa, int l, int r) {
	while (l < r) {
		int i = l, j = l, k = r, a = aa[l + rand_() % (r - l)], tmp;

		while (j < k)
			if (aa[j] == a)
				j++;
			else if (aa[j] < a) {
				tmp = aa[i], aa[i] = aa[j], aa[j] = tmp;
				i++, j++;
			} else {
				k--;
				tmp = aa[j], aa[j] = aa[k], aa[k] = tmp;
			}
		sort(aa, l, i);
		l = k;
	}
}

int main() {
	static int rr[N], dp[N + 1][L + 1], dq[N + 1][L + 1];
	int n, l, i, c, s, ans;

	init();
	scanf("%d%d", &n, &l);
	for (i = 0; i < n; i++)
		scanf("%d", &rr[i]), rr[i]--;
	sort(rr, 0, n);
	dp[0][0] = 1;
	for (i = 0; i < n; i++) {
		int r = rr[i];

		for (c = 0; c <= n; c++)
			memset(dq[c], 0, (l + 1) * sizeof *dq[c]);
		for (c = 0; c <= n; c++)
			for (s = 0; s <= l; s++) {
				int x = dp[c][s];

				if (x == 0)
					continue;
				dq[c + 1][s] = (dq[c + 1][s] + x) % MD;
				if (c > 0 && s + r <= l)
					dq[c][s + r] = (dq[c][s + r] + (long long) x * c * 2) % MD;
				if (c >= 2 && s + r * 2 <= l)
					dq[c - 1][s + r * 2] = (dq[c - 1][s + r * 2] + (long long) x * c * (c - 1)) % MD;
			}
		for (c = 0; c <= n; c++)
			memcpy(dp[c], dq[c], (l + 1) * sizeof *dq[c]);
	}
	ans = 0;
	for (s = 0; s <= l; s++)
		ans = (ans + (long long) dp[1][s] * choose(l - s, n)) % MD;
	printf("%d\n", ans);
	return 0;
}

Compilation message (stderr)

Main.c: In function 'main':
Main.c:57:2: warning: ignoring return value of 'scanf' declared with attribute 'warn_unused_result' [-Wunused-result]
   57 |  scanf("%d%d", &n, &l);
      |  ^~~~~~~~~~~~~~~~~~~~~
Main.c:59:3: warning: ignoring return value of 'scanf' declared with attribute 'warn_unused_result' [-Wunused-result]
   59 |   scanf("%d", &rr[i]), rr[i]--;
      |   ^~~~~~~~~~~~~~~~~~~

• Subtask 1: 10 / 10
• Subtask 2: 20 / 20
• Subtask 3: 30 / 30
• Subtask 4: 50 / 50