| # |
Submission time |
Handle |
Problem |
Language |
Result |
Execution time |
Memory |
| 90523 |
2018-12-22T07:21:01 Z |
szawinis |
Boat (APIO16_boat) |
C++17 |
|
6 ms |
2428 KB |
/**
* code generated by JHelper
* More info: https://github.com/AlexeyDmitriev/JHelper
* @author
*/
#include <bits/stdc++.h>
using namespace std;
#define long long long
const long MOD = 1e9+7, LINF = 1e18 + 1e16;
const int INF = 1e9+1;
const double EPS = 1e-10;
const int dx[4] = {-1, 0, 1, 0}, dy[4] = {0, 1, 0, -1};
const int N = 510;
class APIO16_boat {
void add(long &a, long b) {
a += b;
if(a >= MOD) a -= MOD;
}
long mul(long a, long b) { return a*b % MOD; }
long modPow(long b, long e) {
if(e == 0) return 1;
if(e == 1) return b;
return mul(modPow(mul(b, b), e >> 1), modPow(b, e & 1));
}
int n, a[N], b[N];
pair<int,int> segs[N];
vector<int> vals;
unordered_map<int, int> rev;
long ans, inv[N], dp[N][N];
public:
void solve(istream &cin, ostream &cout) {
cin >> n;
vals.push_back(0);
for(int i = 1; i <= n; i++) {
cin >> a[i] >> b[i];
vals.push_back(a[i]);
vals.push_back(b[i]+1);
}
sort(vals.begin(), vals.end());
vals.resize(unique(vals.begin(), vals.end()) - vals.begin());
for(int i = 0; i < vals.size(); i++) rev[vals[i]] = i;
for(int i = 1; i <= n; i++) segs[i] = {rev[a[i]], rev[b[i]+1]};
inv[0] = 1;
for(int i = 1; i <= n; i++) inv[i] = mul(inv[i-1], modPow(i, MOD-2));
// for(int x: vals) cout << x << ' ';
// cout << endl;
// for(int i = 1; i <= n; i++) cout << segs[i].first << ' ' << segs[i].second << endl;
for(int j = 0; j < vals.size(); j++) dp[0][j] = 1;
for(int i = 1; i <= n; i++) {
for(int j = segs[i].first; j < segs[i].second; j++) {
int cnt = 0;
long f = 1, sum = 0;
for(int k = i-1; k >= 0; k--) {
if(segs[k+1].first <= j && j < segs[k+1].second) {
f = mul(f, vals[j+1] - vals[j] - cnt);
f = mul(f, inv[cnt + 1]);
sum += f;
++cnt;
}
add(dp[i][j], mul(dp[k][j-1], sum));
}
}
partial_sum(dp[i], dp[i] + vals.size(), dp[i]);
add(ans, dp[i][vals.size() - 1]);
}
cout << ans;
}
};
class Solver {
public:
void solve(std::istream& in, std::ostream& out) {
APIO16_boat *obj = new APIO16_boat();
obj->solve(in, out);
delete obj;
}
};
int main() {
ios::sync_with_stdio(false);
cin.tie(0);
Solver solver;
std::istream& in(std::cin);
std::ostream& out(std::cout);
solver.solve(in, out);
return 0;
}
Compilation message
boat.cpp: In member function 'void APIO16_boat::solve(std::istream&, std::ostream&)':
boat.cpp:47:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
for(int i = 0; i < vals.size(); i++) rev[vals[i]] = i;
~~^~~~~~~~~~~~~
boat.cpp:57:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
for(int j = 0; j < vals.size(); j++) dp[0][j] = 1;
~~^~~~~~~~~~~~~
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Incorrect |
5 ms |
2424 KB |
Output isn't correct |
| 2 |
Halted |
0 ms |
0 KB |
- |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Incorrect |
5 ms |
2424 KB |
Output isn't correct |
| 2 |
Halted |
0 ms |
0 KB |
- |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Incorrect |
6 ms |
2428 KB |
Output isn't correct |
| 2 |
Halted |
0 ms |
0 KB |
- |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Incorrect |
5 ms |
2424 KB |
Output isn't correct |
| 2 |
Halted |
0 ms |
0 KB |
- |
