Submission #68134

#	Time	Username	Problem	Language	Result	Execution time	Memory
68134		funcsr	Boat (APIO16_boat)	C++17	100 / 100	1201 ms	5556 KiB

boat

#include <cstdio>
#include <iostream>
#include <algorithm>
#include <string>
#include <cstring>
#include <vector>
#include <queue>
#include <set>
#include <map>
#include <cmath>
#include <iomanip>
#include <cassert>
#include <bitset>
using namespace std;

typedef pair<int, int> P;
#define rep(i, n) for (int i=0; i<(n); i++)
#define all(c) (c).begin(), (c).end()
#define uniq(c) c.erase(unique(all(c)), (c).end())
#define index(xs, x) (int)(lower_bound(all(xs), x) - xs.begin())
#define _1 first
#define _2 second
#define pb push_back
#define INF 1145141919
#define MOD 1000000007
inline void add(int &x, int v) { x += v; if (x >= MOD) x -= MOD; }
inline int mul(int x, int y) { return (1LL*x*y)%MOD; }
int modpow(int x, int k) {
  int a = 1;
  while (k) {
    if (k&1) a = mul(a, x);
    x = mul(x, x);
    k >>= 1;
  }
  return a;
}

int N;
int A[500], B[500];
int inv[501];
int dp[2][1000][501];

signed main() {
  ios::sync_with_stdio(false); cin.tie(0);
  cin >> N;
  rep(k, N+1) inv[k] = modpow(k, MOD-2);
  vector<int> ys;
  rep(i, N) cin >> A[i] >> B[i], ys.pb(A[i]), ys.pb(B[i]+1);
  sort(all(ys)); uniq(ys);
  rep(i, N) A[i] = index(ys, A[i]), B[i] = index(ys, B[i]+1)-1;

  dp[0][0][0] = 1;
  rep(i, N) {
    rep(j, ys.size()-1) rep(k, i+2) dp[1][j][k] = dp[0][j][k];
    for (int j=A[i]; j<=B[i]; j++) rep(k, i+1) add(dp[1][j][k+1], mul(dp[0][j][k], mul(ys[j+1]-ys[j]-k, inv[k+1])));
    int s = 0;
    rep(t, B[i]+1) {
      if (t >= A[i]) add(dp[1][t][1], mul(ys[t+1]-ys[t], s));
      rep(k, i+1) add(s, dp[0][t][k]);
    }
    swap(dp[0], dp[1]);
  }
  int s = MOD-1;
  rep(j, ys.size()-1) rep(k, N+1) add(s, dp[0][j][k]);
  cout << s << "\n";
  return 0;
}

Compilation message (stderr)

boat.cpp: In function 'int main()':
boat.cpp:17:34: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
 #define rep(i, n) for (int i=0; i<(n); i++)
                                  ^
boat.cpp:54:5: note: in expansion of macro 'rep'
     rep(j, ys.size()-1) rep(k, i+2) dp[1][j][k] = dp[0][j][k];
     ^~~
boat.cpp:17:34: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
 #define rep(i, n) for (int i=0; i<(n); i++)
                                  ^
boat.cpp:64:3: note: in expansion of macro 'rep'
   rep(j, ys.size()-1) rep(k, N+1) add(s, dp[0][j][k]);
   ^~~

• Subtask 1: 9 / 9
• Subtask 2: 22 / 22
• Subtask 3: 27 / 27
• Subtask 4: 42 / 42