Submission #48534

#	Time	Username	Problem	Language	Result	Execution time	Memory
48534		Kmcode	Boat (APIO16_boat)	C++14	100 / 100	1430 ms	21208 KiB

boat

#include "bits/stdc++.h"
using namespace std;

#define MOD 1000000007

#define MAX 1102


int n;

vector<pair<int, int> > v;
vector<int> vv;

long long int dp[MAX][MAX];

long long int way[MAX][MAX];

long long int c[MAX][MAX];

long long int ppow(long long int i, long long int j) {
	long long int res = 1;
	while (j) {
		if ((j & 1LL)) {
			res *= i;
			if (res >= MOD)res %= MOD;
		}
		i *= i;
		if (i >= MOD)i %= MOD;
		j >>= 1LL;
	}
	return res;
}

long long int k[MAX];

int main() {
	k[0] = 1;
	for (int i = 1; i < MAX; i++) {
		k[i] = k[i - 1];
		k[i] *= (long long int)(i);
		if (k[i] >= MOD)k[i] %= MOD;
	}
	for (int i = 0; i < MAX; i++) {
		k[i] = ppow(k[i], MOD - 2);
	}
	c[0][0] = 1;
	for (int i = 0; i + 1 < MAX; i++) {
		for (int j = 0; j <= i; j++) {
			c[i + 1][j] += c[i][j];
			c[i + 1][j + 1] += c[i][j];
			if (c[i + 1][j] >= MOD)c[i + 1][j] -= MOD;
			if (c[i + 1][j + 1] >= MOD)c[i + 1][j + 1] -= MOD;
		}
	}
	cin >> n;
	vv.push_back(0);
	for (int i = 0; i < n; i++) {
		int a, b;
		scanf("%d%d", &a, &b);
		vv.push_back(a), vv.push_back(b+1);
		v.push_back(make_pair(a, b));
	}
	sort(vv.begin(), vv.end());
	vv.erase(unique(vv.begin(), vv.end()), vv.end());
	vv.push_back(vv.back() + 1);
	dp[0][0] = 1;
	for (int i = 0; i + 1 < vv.size(); i++) {
		long long int rng = vv[i + 1] - vv[i];
		long long int up = 1;
		long long int dw = 0;
		for (int j = 1; j <= 500; j++) {
			if (rng < j)break;
			up *= (long long int)(rng - j + 1LL);
			if (up >= MOD)up %= MOD;
			dw = k[j];
			dw *= up;
			if (dw >= MOD)dw %= MOD;
			way[i][j] = dw;
		}
		for (int j = 500; j >= 1; j--) {
			long long int tmp = 0;
			for (int k = j; k >= 1; k--) {
				tmp += way[i][k] * c[j - 1][k - 1];
				if (tmp >= MOD)tmp %= MOD;
			}
			way[i][j] = tmp;
			if (tmp < 0LL)while (1);
		}
	}
	long long int AA = 0;
	for (int i = 0; i < v.size(); i++) {
		long long int su = 0;
		for (int j = 0; j + 1 < vv.size(); j++) {
			int valid = 0;
			for (int k = i; k < v.size(); k++) {
				if (v[k].first <= vv[j] && vv[j + 1] - 1 <= v[k].second) {
					valid++;
					if (su < 0LL)while(1);
					dp[k + 1][j] += su*way[j][valid];
					AA += su*way[j][valid];
					if (AA >= MOD)AA %= MOD;
					if (dp[k + 1][j] >= MOD)dp[k + 1][j] %= MOD;
				}
			}
			su += dp[i][j];
			if (su >= MOD)su %= MOD;
		}
	}
	if (AA < 0LL)exit(1);
	printf("%lld\n", AA);
	return 0;
}

Compilation message (stderr)

boat.cpp: In function 'int main()':
boat.cpp:67:24: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for (int i = 0; i + 1 < vv.size(); i++) {
                  ~~~~~~^~~~~~~~~~~
boat.cpp:91:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for (int i = 0; i < v.size(); i++) {
                  ~~^~~~~~~~~~
boat.cpp:93:25: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   for (int j = 0; j + 1 < vv.size(); j++) {
                   ~~~~~~^~~~~~~~~~~
boat.cpp:95:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
    for (int k = i; k < v.size(); k++) {
                    ~~^~~~~~~~~~
boat.cpp:59:8: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   scanf("%d%d", &a, &b);
   ~~~~~^~~~~~~~~~~~~~~~

• Subtask 1: 9 / 9
• Subtask 2: 22 / 22
• Subtask 3: 27 / 27
• Subtask 4: 42 / 42