Submission #1098058

#	Time	Username	Problem	Language	Result	Execution time	Memory
1098058		VinhLuu	Trains (BOI24_trains)	C++17	16 / 100	14 ms	2528 KiB

Main

#include <bits/stdc++.h>
//#define int long long
#define ll long long
#define fi first
#define se second
#define all(vin) vin.begin(), vin.end()

using namespace std;

typedef pair<int,int> pii;
typedef pair<pii,int> tp;
const int N = 1e5 + 2;
//const int oo = -1e16;
const int mod = 1e9 + 7;

int n, d[N], x[N], block, g[318][N], f[N];

void get(int &x,int y){
  x = (x + y) % mod;
}

signed main(){
  ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
  #define task "v"
  if(fopen(task ".inp","r")){
    freopen(task ".inp","r",stdin);
    freopen(task ".out","w",stdout);
  }

  cin >> n;
  block = sqrt(n);
  vector<int> vr;
  for(int i = 1; i <= n; i ++){
    cin >> d[i] >> x[i];
    if(d[i] <= block) vr.push_back(d[i]);
  }
  sort(all(vr)); vr.resize(unique(all(vr)) - vr.begin());
  for(int i = 1; i <= n; i ++) f[i] = 1;
  for(int i = n; i >= 1; i --){
    if(d[i] > block){
      for(int j = 1; j <= x[i] && i + j * d[i] <= n; j ++)
        get(f[i], f[i + j * d[i]]);

    }else{
      int val = 0;
      if(x[i] && i + (x[i] + 1) * d[i] <= n) val = (mod - g[d[i]][i + (x[i] + 1) * d[i]]) % mod;
      if(x[i]) get(f[i], (g[d[i]][i + d[i]] + val) % mod);
    }
    for(auto j : vr){
      get(g[j][i], f[i] + (i + j <= n ? g[j][i + j] : 0));
    }
  }
  cout << f[1];
}

Compilation message (stderr)

Main.cpp: In function 'int main()':
Main.cpp:26:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   26 |     freopen(task ".inp","r",stdin);
      |     ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~
Main.cpp:27:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   27 |     freopen(task ".out","w",stdout);
      |     ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 0 / 8
• Subtask 2: 0 / 13
• Subtask 3: 16 / 16
• Subtask 4: 0 / 34
• Subtask 5: 0 / 29