#include <bits/stdc++.h>
using namespace std;
const int mod = 1e9 + 7;
int segs[250000],dp[250000];
int length[1001];
int segl[1001];
int l[500],r[500];
int dp2[1001],dp3[1001],dp4[1001];;
int inv[250000];
int p(int a,int b){
int r = 1;
while(b > 0){
if(b%2 == 1)r = 1ll*r*a%mod;
a = 1ll*a*a%mod;
b/=2;
}
return r;
}
void precalc(){
for(int i = 0;i <= 250000;i++){
inv[i] = p(i,mod - 2);
}
}
int main(){
int n,i,cnt = 1,j,cnt2 = 0,ans = 0;
cin>>n;
for(i = 0;i < n;i++){
cin>>l[i]>>r[i];
segl[i*2] = l[i];
segl[i*2+1] = r[i] + 1;
}
sort(segl,segl + 2*n);
for(i = 1;i < 2*n;i++){
if(segl[i] != segl[cnt - 1]){
segl[cnt++] = segl[i];
}
}
for(i = 0;i < n;i++){
for(j = cnt - 1;j >= 0;j--){
if(l[i] <= segl[j] && segl[j] <= r[i]){
segs[cnt2++] = j;
length[j] = segl[j + 1] - segl[j];
}
}
}
segs[cnt2++] = cnt;
length[cnt] = 1;
for(i = 0;i < cnt2;i++){
for(j = 0;j < 1001;j++){
dp2[j] = length[j];
dp3[j] = length[j];
dp4[j] = 1;
}
dp[i] = 1;
for(j = i - 1;j >= 0;j--){
if(segs[j] < segs[i]){
dp[i] = (dp[i] + 1ll*dp[j]*dp2[segs[j]])%mod;
dp3[segs[j]] = 1ll*dp3[segs[j]]*(length[segs[j]] - dp4[segs[j]])%mod*inv[dp4[segs[j]] + 1]%mod;
dp4[segs[j]]++;
if(dp4[segs[j]] > length[segs[j]])dp2[segs[j]]+=dp3[segs[j]];
dp2[segs[j]]%=mod;
}
}
}
ans = dp[cnt2 - 1] - 1;
cout<<ans;
return 0;
}
Compilation message
boat.cpp: In function 'void precalc()':
boat.cpp:21:16: warning: iteration 250000 invokes undefined behavior [-Waggressive-loop-optimizations]
21 | inv[i] = p(i,mod - 2);
| ~~~~~~~^~~~~~~~~~~~~~
boat.cpp:20:21: note: within this loop
20 | for(int i = 0;i <= 250000;i++){
| ~~^~~~~~~~~
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
3 ms |
320 KB |
Output is correct |
2 |
Correct |
3 ms |
340 KB |
Output is correct |
3 |
Correct |
4 ms |
340 KB |
Output is correct |
4 |
Correct |
2 ms |
340 KB |
Output is correct |
5 |
Correct |
2 ms |
340 KB |
Output is correct |
6 |
Correct |
3 ms |
340 KB |
Output is correct |
7 |
Correct |
3 ms |
320 KB |
Output is correct |
8 |
Correct |
3 ms |
340 KB |
Output is correct |
9 |
Correct |
3 ms |
316 KB |
Output is correct |
10 |
Correct |
3 ms |
360 KB |
Output is correct |
11 |
Correct |
3 ms |
340 KB |
Output is correct |
12 |
Correct |
3 ms |
320 KB |
Output is correct |
13 |
Correct |
3 ms |
340 KB |
Output is correct |
14 |
Correct |
3 ms |
340 KB |
Output is correct |
15 |
Correct |
3 ms |
340 KB |
Output is correct |
16 |
Correct |
2 ms |
340 KB |
Output is correct |
17 |
Correct |
2 ms |
340 KB |
Output is correct |
18 |
Correct |
2 ms |
340 KB |
Output is correct |
19 |
Correct |
2 ms |
340 KB |
Output is correct |
20 |
Correct |
2 ms |
340 KB |
Output is correct |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
3 ms |
320 KB |
Output is correct |
2 |
Correct |
3 ms |
340 KB |
Output is correct |
3 |
Correct |
4 ms |
340 KB |
Output is correct |
4 |
Correct |
2 ms |
340 KB |
Output is correct |
5 |
Correct |
2 ms |
340 KB |
Output is correct |
6 |
Correct |
3 ms |
340 KB |
Output is correct |
7 |
Correct |
3 ms |
320 KB |
Output is correct |
8 |
Correct |
3 ms |
340 KB |
Output is correct |
9 |
Correct |
3 ms |
316 KB |
Output is correct |
10 |
Correct |
3 ms |
360 KB |
Output is correct |
11 |
Correct |
3 ms |
340 KB |
Output is correct |
12 |
Correct |
3 ms |
320 KB |
Output is correct |
13 |
Correct |
3 ms |
340 KB |
Output is correct |
14 |
Correct |
3 ms |
340 KB |
Output is correct |
15 |
Correct |
3 ms |
340 KB |
Output is correct |
16 |
Correct |
2 ms |
340 KB |
Output is correct |
17 |
Correct |
2 ms |
340 KB |
Output is correct |
18 |
Correct |
2 ms |
340 KB |
Output is correct |
19 |
Correct |
2 ms |
340 KB |
Output is correct |
20 |
Correct |
2 ms |
340 KB |
Output is correct |
21 |
Execution timed out |
2056 ms |
1156 KB |
Time limit exceeded |
22 |
Halted |
0 ms |
0 KB |
- |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Incorrect |
100 ms |
368 KB |
Output isn't correct |
2 |
Halted |
0 ms |
0 KB |
- |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
3 ms |
320 KB |
Output is correct |
2 |
Correct |
3 ms |
340 KB |
Output is correct |
3 |
Correct |
4 ms |
340 KB |
Output is correct |
4 |
Correct |
2 ms |
340 KB |
Output is correct |
5 |
Correct |
2 ms |
340 KB |
Output is correct |
6 |
Correct |
3 ms |
340 KB |
Output is correct |
7 |
Correct |
3 ms |
320 KB |
Output is correct |
8 |
Correct |
3 ms |
340 KB |
Output is correct |
9 |
Correct |
3 ms |
316 KB |
Output is correct |
10 |
Correct |
3 ms |
360 KB |
Output is correct |
11 |
Correct |
3 ms |
340 KB |
Output is correct |
12 |
Correct |
3 ms |
320 KB |
Output is correct |
13 |
Correct |
3 ms |
340 KB |
Output is correct |
14 |
Correct |
3 ms |
340 KB |
Output is correct |
15 |
Correct |
3 ms |
340 KB |
Output is correct |
16 |
Correct |
2 ms |
340 KB |
Output is correct |
17 |
Correct |
2 ms |
340 KB |
Output is correct |
18 |
Correct |
2 ms |
340 KB |
Output is correct |
19 |
Correct |
2 ms |
340 KB |
Output is correct |
20 |
Correct |
2 ms |
340 KB |
Output is correct |
21 |
Execution timed out |
2056 ms |
1156 KB |
Time limit exceeded |
22 |
Halted |
0 ms |
0 KB |
- |