#include <bits/stdc++.h>
using namespace std;
#define X first
#define Y second
#define mp make_pair
#define pb push_back
typedef long long ll;
typedef pair <int, int> pii;
typedef pair <int, pii> pip;
typedef pair <pii, int> ppi;
typedef pair <ll, ll> pll;
const int INF=0x3f3f3f3f;
const int N=105;
const int MOD=1e9+7;
int n, m;
int A[N], B[N], povrh[2*N][N], siz[2*N];
pii p[2*N];
vector <int> v;
map <int, int> kraj;
int dp[N][2*N][N][2];
#define DEBUG 0
int add(int a, int b) {
a+=b;
if (a>=MOD) a-=MOD;
return a;
}
int mul(int a, int b) {
return (ll)a*b%MOD;
}
int pot(int baza, int ex) {
int ret=1;
while (ex) {
if (ex%2) ret=mul(ret, baza);
baza=mul(baza, baza);
ex/=2;
}
return ret;
}
int divv(int a, int b) {
return mul(a, pot(b, MOD-2));
}
void prec() {
for (int i=0; i<m; ++i) {
povrh[i][0]=1;
for (int j=1; j<=min(n, siz[i]); ++j) povrh[i][j]=divv(mul(povrh[i][j-1], siz[i]-j+1), j);
}
}
int rek(int pos, int gr, int kol, int fl) {
if (kol>siz[gr]) return 0;
if (gr>=m) return 0;
if (pos==n) return (!!kol)*povrh[gr][kol];
int &ret=dp[pos][gr][kol][fl];
if (ret!=-1) return ret;
ret=0;
ret=add(ret, mul(povrh[gr][kol], rek(pos, gr+1, 0, 0))); //nova grupa
if (fl) ret=add(ret, rek(pos+1, gr, kol, 1)); //ne stavljam
if (p[gr].X>=A[pos] && p[gr].Y<=B[pos]) ret=add(ret, rek(pos+1, gr, kol+1, 1));
#if DEBUG
printf("pos: %d, gr: %d, kol: %d, fl: %d ===== %d\n", pos, gr, kol, fl, ret);
#endif //DEBUG
return ret;
}
void solve() {
sort(v.begin(), v.end());
v.erase(unique(v.begin(), v.end()), v.end());
m=v.size();
p[0]=mp(v[0], v[1]-1);
for (int i=1; i<m; ++i) p[i]=mp(p[i-1].Y+1, max(v[i]-1+kraj[v[i]], p[i-1].Y+1));
for (int i=0; i<m; ++i) siz[i]=p[i].Y-p[i].X+1;
#if DEBUG
printf("\n");
for (int i=0; i<m; ++i) printf("[%d, %d]\n", p[i].X, p[i].Y);
#endif // DEBUG
prec();
memset(dp, -1, sizeof dp);
// int sol=add(rek(0, 0, 0, 1), MOD-1);
printf("%d\n", rek(0, 0, 0, 1));
}
void load() {
scanf("%d", &n);
for (int i=0; i<n; ++i) {
scanf("%d %d", &A[i], &B[i]);
v.pb(A[i]); v.pb(B[i]);
kraj[B[i]]=1;
}
}
int main() {
load();
solve();
return 0;
}
Compilation message
boat.cpp: In function 'void load()':
boat.cpp:100:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
100 | scanf("%d", &n);
| ~~~~~^~~~~~~~~~
boat.cpp:102:14: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
102 | scanf("%d %d", &A[i], &B[i]);
| ~~~~~^~~~~~~~~~~~~~~~~~~~~~~
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Runtime error |
1745 ms |
96304 KB |
Execution killed with signal 11 |
2 |
Halted |
0 ms |
0 KB |
- |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Runtime error |
1745 ms |
96304 KB |
Execution killed with signal 11 |
2 |
Halted |
0 ms |
0 KB |
- |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Incorrect |
30 ms |
18540 KB |
Output isn't correct |
2 |
Halted |
0 ms |
0 KB |
- |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Runtime error |
1745 ms |
96304 KB |
Execution killed with signal 11 |
2 |
Halted |
0 ms |
0 KB |
- |