#include<bits/stdc++.h>
using namespace std;
const int nax = 503;
const int mod = 1e9 + 7;
vector<int>ind[nax*2];
int a[nax], b[nax];
int n, m;
int dp[nax*2][nax];
vector<int>imp;
int add(int a, int b) {
a += b;
if(a>=mod) a -= mod;
return a;
}
int mul(int a, int b) {
return (a * 1LL * b) % mod;
}
int quickpow(int a, int b) {
int ret = 1;
while(b) {
if(b&1) ret = mul(ret, a);
a = mul(a, a);
b >>= 1;
}
return ret;
}
int C(int n, int r) {
int ret = 1;
for(int i=n-r+1; i<=n; ++i) {
ret = mul(ret, i);
}
for(int i=1; i<=r; ++i) {
ret = mul(ret, quickpow(i, mod-2));
}
return ret;
}
int solve(int i, int prv) {
if(i==m-1) return prv>0;
int &ret = dp[i][prv];
if(ret!=-1) return ret;
ret = 0;
ret = solve(i+1, prv);
int len = imp[i+1]-imp[i];
for(int mx=0, cur_op=0; mx<ind[i].size(); ++mx) {
if(ind[i][mx]<=prv) continue;
int cur = solve(i+1, ind[i][mx]);
for(int take=0; take<=min(cur_op, len-1); ++take) {
ret = add(ret, mul(cur, mul(C(cur_op, take), C(len, take+1))));
}
cur_op++;
}
return ret;
}
void PlayGround() {
cin>>n;
set<int>pts;
for(int i=1; i<=n; ++i) {
cin>>a[i]>>b[i];
pts.insert(a[i]);
pts.insert(b[i]+1);
}
for(int x : pts) {
imp.push_back(x);
}
m = imp.size();
for(int i=0; i<m; ++i) {
for(int j=1; j<=n; ++j) {
if(imp[i]>=a[j] && imp[i]<=b[j]) {
ind[i].push_back(j);
}
}
}
// for(int i=0; i<m; ++i) {
// cerr<<imp[i]<<' ';
// } cerr<<endl;
memset(dp, -1, sizeof dp);
cout<<solve(0, 0)<<'\n';
// cerr << "Time elapsed: " << 1.0 * clock() / CLOCKS_PER_SEC << " s.\n";
}
int main() {
ios_base::sync_with_stdio(false);
cin.tie(NULL);
PlayGround();
return 0;
}
Compilation message
boat.cpp: In function 'int solve(int, int)':
boat.cpp:50:29: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
50 | for(int mx=0, cur_op=0; mx<ind[i].size(); ++mx) {
| ~~^~~~~~~~~~~~~~
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
21 ms |
2516 KB |
Output is correct |
2 |
Correct |
17 ms |
2544 KB |
Output is correct |
3 |
Correct |
20 ms |
2540 KB |
Output is correct |
4 |
Correct |
17 ms |
2544 KB |
Output is correct |
5 |
Correct |
18 ms |
2544 KB |
Output is correct |
6 |
Correct |
29 ms |
2528 KB |
Output is correct |
7 |
Correct |
26 ms |
2516 KB |
Output is correct |
8 |
Correct |
27 ms |
2516 KB |
Output is correct |
9 |
Correct |
26 ms |
2516 KB |
Output is correct |
10 |
Correct |
26 ms |
2516 KB |
Output is correct |
11 |
Correct |
27 ms |
2516 KB |
Output is correct |
12 |
Correct |
27 ms |
2516 KB |
Output is correct |
13 |
Correct |
28 ms |
2516 KB |
Output is correct |
14 |
Correct |
26 ms |
2536 KB |
Output is correct |
15 |
Correct |
26 ms |
2516 KB |
Output is correct |
16 |
Correct |
13 ms |
2260 KB |
Output is correct |
17 |
Correct |
14 ms |
2280 KB |
Output is correct |
18 |
Correct |
13 ms |
2376 KB |
Output is correct |
19 |
Correct |
14 ms |
2384 KB |
Output is correct |
20 |
Correct |
14 ms |
2260 KB |
Output is correct |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
21 ms |
2516 KB |
Output is correct |
2 |
Correct |
17 ms |
2544 KB |
Output is correct |
3 |
Correct |
20 ms |
2540 KB |
Output is correct |
4 |
Correct |
17 ms |
2544 KB |
Output is correct |
5 |
Correct |
18 ms |
2544 KB |
Output is correct |
6 |
Correct |
29 ms |
2528 KB |
Output is correct |
7 |
Correct |
26 ms |
2516 KB |
Output is correct |
8 |
Correct |
27 ms |
2516 KB |
Output is correct |
9 |
Correct |
26 ms |
2516 KB |
Output is correct |
10 |
Correct |
26 ms |
2516 KB |
Output is correct |
11 |
Correct |
27 ms |
2516 KB |
Output is correct |
12 |
Correct |
27 ms |
2516 KB |
Output is correct |
13 |
Correct |
28 ms |
2516 KB |
Output is correct |
14 |
Correct |
26 ms |
2536 KB |
Output is correct |
15 |
Correct |
26 ms |
2516 KB |
Output is correct |
16 |
Correct |
13 ms |
2260 KB |
Output is correct |
17 |
Correct |
14 ms |
2280 KB |
Output is correct |
18 |
Correct |
13 ms |
2376 KB |
Output is correct |
19 |
Correct |
14 ms |
2384 KB |
Output is correct |
20 |
Correct |
14 ms |
2260 KB |
Output is correct |
21 |
Execution timed out |
2064 ms |
3284 KB |
Time limit exceeded |
22 |
Halted |
0 ms |
0 KB |
- |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Execution timed out |
2036 ms |
2388 KB |
Time limit exceeded |
2 |
Halted |
0 ms |
0 KB |
- |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
21 ms |
2516 KB |
Output is correct |
2 |
Correct |
17 ms |
2544 KB |
Output is correct |
3 |
Correct |
20 ms |
2540 KB |
Output is correct |
4 |
Correct |
17 ms |
2544 KB |
Output is correct |
5 |
Correct |
18 ms |
2544 KB |
Output is correct |
6 |
Correct |
29 ms |
2528 KB |
Output is correct |
7 |
Correct |
26 ms |
2516 KB |
Output is correct |
8 |
Correct |
27 ms |
2516 KB |
Output is correct |
9 |
Correct |
26 ms |
2516 KB |
Output is correct |
10 |
Correct |
26 ms |
2516 KB |
Output is correct |
11 |
Correct |
27 ms |
2516 KB |
Output is correct |
12 |
Correct |
27 ms |
2516 KB |
Output is correct |
13 |
Correct |
28 ms |
2516 KB |
Output is correct |
14 |
Correct |
26 ms |
2536 KB |
Output is correct |
15 |
Correct |
26 ms |
2516 KB |
Output is correct |
16 |
Correct |
13 ms |
2260 KB |
Output is correct |
17 |
Correct |
14 ms |
2280 KB |
Output is correct |
18 |
Correct |
13 ms |
2376 KB |
Output is correct |
19 |
Correct |
14 ms |
2384 KB |
Output is correct |
20 |
Correct |
14 ms |
2260 KB |
Output is correct |
21 |
Execution timed out |
2064 ms |
3284 KB |
Time limit exceeded |
22 |
Halted |
0 ms |
0 KB |
- |