#include<bits/stdc++.h>
#define I inline void
using ll = long long ;
using ld = long double ;
using namespace std ;
const int N = 1e6 + 7 , mod = 1e9+7 ;
// how interesting!
int n , m;
vector<int> lst ;
int L[N] , R[N] , S[N] ;
int dp[001][501] ;
ll faspow(ll x , ll y){
if(!y)return 1ll ;
ll ret = faspow(x , y/2) ;
ret = 1ll * ret *ret %mod ;
if(y&1)ret = 1ll * ret * x %mod ;
return ret ;
}
ll inv[N] ;
int main(){
ios_base::sync_with_stdio(0) ;
cin.tie(0) ;
//freopen("in.in" , "r" , stdin) ;
inv[1] = 1ll ;
for(int i = 2; i < N; i++) inv[i] = (mod/i) * (mod-inv[mod%i]) % mod;
cin >> n ;
for(int i = 1 ;i <= n;i++){
cin >> L[i] >> R[i] ;
R[i] ++ ;
lst.push_back(L[i]) ;
lst.push_back(R[i]) ;
}
sort(lst.begin() , lst.end()) ;
lst.resize(unique(lst.begin() , lst.end()) - lst.begin()) ;
for(int i = 1 ;i <= n ;i++){
L[i] = lower_bound(lst.begin() , lst.end() , L[i]) - lst.begin() + 1;
R[i] = lower_bound(lst.begin() , lst.end() , R[i]) - lst.begin() + 1;
}
int w = lst.size() ;
for(int i = 1 ;i < w ;i++){
S[i] = lst[i] - lst[i-1] ;
}
dp[0][0] = 1ll ;
for(int i = 1 ;i < w ;i++){
dp[i][0] = 1ll ;
for(int j = 1 ;j <=n ;j++){
int count = 1;
ll mul = S[i] ;
dp[i][j] = dp[i-1][j] ;
if(i < L[j] || i >= R[j])
continue ;
for(int k = j -1 ; k >= 0 ; k --){
dp[i][j] = (dp[i][j] + (mul * dp[i-1][k]) %mod ) %mod ;
if(L[k] <= i && R[k] > i){
mul = 1ll * mul * (S[i] + count) %mod ;
mul = 1ll * mul * inv[count +1] %mod ;
count ++ ;
}
}
}
}
ll ans = 0ll ;
for(int i = 1 ; i<=n ;i++){
ans = (ans + dp[w-1][i]) %mod ;
}
cout<< ans ;
return 0 ;
}
Compilation message
boat.cpp: In function 'int main()':
boat.cpp:61:7: warning: array subscript 1 is above array bounds of 'int [1][501]' [-Warray-bounds]
61 | dp[i][0] = 1ll ;
| ~~~~^
boat.cpp:17:5: note: while referencing 'dp'
17 | int dp[001][501] ;
| ^~
boat.cpp:68:8: warning: array subscript 1 is above array bounds of 'int [1][501]' [-Warray-bounds]
68 | dp[i][j] = dp[i-1][j] ;
| ~~~~^
boat.cpp:17:5: note: while referencing 'dp'
17 | int dp[001][501] ;
| ^~
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Incorrect |
25 ms |
10104 KB |
Output isn't correct |
2 |
Halted |
0 ms |
0 KB |
- |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Incorrect |
25 ms |
10104 KB |
Output isn't correct |
2 |
Halted |
0 ms |
0 KB |
- |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Incorrect |
24 ms |
8576 KB |
Output isn't correct |
2 |
Halted |
0 ms |
0 KB |
- |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Incorrect |
25 ms |
10104 KB |
Output isn't correct |
2 |
Halted |
0 ms |
0 KB |
- |