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Submission #25199

# Submission time Handle Problem Language Result Execution time Memory
25199 2017-06-20T17:36:01 Z gabrielsimoes Boat (APIO16_boat) C++14
0 / 100
 16 ms 2052 KB 
#include <bits/stdc++.h>
using namespace std;

typedef long long ll;
const ll MOD = 1000000007;
const int MAXN = 501;
const int MAX = 1e6+10;

#define mod(a, b) (((a)*(b)) % MOD)

ll invpow(ll a, ll b = MOD-2) {
	ll ret = 1;
	ll prod = a;
	for (int i = 0; i <= 30; i++) {
		if ((1LL << i) & b)
			ret = (ret * prod) % MOD;
		prod = (prod*prod) % MOD;
	}
	return ret;
}		

int n;
ll a[MAXN], b[MAXN];
vector<ll> v;

ll inv[MAXN];
ll bin[MAXN], c[MAXN];
ll dp[MAXN], sum[MAXN];

int main()
{
	scanf("%d", &n);
	for (int i = 0; i < n; i++) {
		scanf("%lld %lld", &a[i], &b[i]);
		b[i]++;
		v.push_back(a[i]);
		v.push_back(b[i]);
	}
	
	sort(v.begin(), v.end());
	v.resize(unique(v.begin(), v.end()) - v.begin());
	
	for (int i = 1; i <= n; i++)
		inv[i] = invpow(i);
	
	for (int i = 0; i < n; i++) {
		a[i] = lower_bound(v.begin(), v.end(), a[i]) - v.begin();
		b[i] = lower_bound(v.begin(), v.end(), b[i]) - v.begin();
	}

	for (int region = 1; region < v.size(); region++) {
		ll L = v[region] - v[region-1];
		
		bin[0] = 1;
		for (int i = 1; i <= n; i++)
			bin[i] = i <= L ? mod(mod(L - i + 1, inv[i]), bin[i-1])
							: 0;
			
		c[1] = L;
		for (int i = 2; i <= n; i++)
            c[i] = c[i-1]*(L+i-1) %MOD * inv[i] %MOD;
			
		sum[0] = 1;
		for (int i = 1; i <= n; i++)
			sum[i] = (dp[i-1] + sum[i-1]) % MOD;
		
		for (int i = n-1; i >= 0; i--) {
			if (region <= a[i] || region > b[i]) continue;
			
			for (int k = i; k >= 0; k--) {
				if (region <= a[k] || region > b[k]) continue;
				dp[i] += mod(c[i - k + 1], sum[k]);
			}
			
			dp[i] %= MOD;
		}
	}
	
	ll ans = 0;
	for (int i = 0; i < n; i++)
		ans += dp[i];
	printf("%lld\n", ans % MOD);
}

Compilation message

boat.cpp: In function 'int main()':
boat.cpp:51:30: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for (int region = 1; region < v.size(); region++) {
                              ^
boat.cpp:32:17: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%d", &n);
                 ^
boat.cpp:34:35: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   scanf("%lld %lld", &a[i], &b[i]);
                                   ^

Subtask #1
0 / 9.0

# Verdict Execution time Memory Grader output
1 Correct 16 ms 2052 KB Output is correct
2 Correct 16 ms 2052 KB Output is correct
3 Correct 13 ms 2052 KB Output is correct
4 Correct 13 ms 2052 KB Output is correct
5 Correct 13 ms 2052 KB Output is correct
6 Correct 13 ms 2052 KB Output is correct
7 Correct 13 ms 2052 KB Output is correct
8 Correct 16 ms 2052 KB Output is correct
9 Correct 16 ms 2052 KB Output is correct
10 Correct 13 ms 2052 KB Output is correct
11 Correct 13 ms 2052 KB Output is correct
12 Correct 13 ms 2052 KB Output is correct
13 Correct 13 ms 2052 KB Output is correct
14 Correct 16 ms 2052 KB Output is correct
15 Correct 13 ms 2052 KB Output is correct
16 Incorrect 3 ms 2052 KB Output isn't correct
17 Halted 0 ms 0 KB -

Subtask #2
0 / 22.0

# Verdict Execution time Memory Grader output
1 Correct 16 ms 2052 KB Output is correct
2 Correct 16 ms 2052 KB Output is correct
3 Correct 13 ms 2052 KB Output is correct
4 Correct 13 ms 2052 KB Output is correct
5 Correct 13 ms 2052 KB Output is correct
6 Correct 13 ms 2052 KB Output is correct
7 Correct 13 ms 2052 KB Output is correct
8 Correct 16 ms 2052 KB Output is correct
9 Correct 16 ms 2052 KB Output is correct
10 Correct 13 ms 2052 KB Output is correct
11 Correct 13 ms 2052 KB Output is correct
12 Correct 13 ms 2052 KB Output is correct
13 Correct 13 ms 2052 KB Output is correct
14 Correct 16 ms 2052 KB Output is correct
15 Correct 13 ms 2052 KB Output is correct
16 Incorrect 3 ms 2052 KB Output isn't correct
17 Halted 0 ms 0 KB -

Subtask #3
0 / 27.0

# Verdict Execution time Memory Grader output
1 Incorrect 0 ms 2052 KB Output isn't correct
2 Halted 0 ms 0 KB -

Subtask #4
0 / 42.0

# Verdict Execution time Memory Grader output
1 Correct 16 ms 2052 KB Output is correct
2 Correct 16 ms 2052 KB Output is correct
3 Correct 13 ms 2052 KB Output is correct
4 Correct 13 ms 2052 KB Output is correct
5 Correct 13 ms 2052 KB Output is correct
6 Correct 13 ms 2052 KB Output is correct
7 Correct 13 ms 2052 KB Output is correct
8 Correct 16 ms 2052 KB Output is correct
9 Correct 16 ms 2052 KB Output is correct
10 Correct 13 ms 2052 KB Output is correct
11 Correct 13 ms 2052 KB Output is correct
12 Correct 13 ms 2052 KB Output is correct
13 Correct 13 ms 2052 KB Output is correct
14 Correct 16 ms 2052 KB Output is correct
15 Correct 13 ms 2052 KB Output is correct
16 Incorrect 3 ms 2052 KB Output isn't correct
17 Halted 0 ms 0 KB -