Submission #1033568

#	Time	Username	Problem	Language	Result	Execution time	Memory
1033568		reginox	Trains (BOI24_trains)	C++17	0 / 100	11 ms	8796 KiB

Main

#include<bits/stdc++.h>
#define ll long long
#define ld long double
#define all(v) begin(v), end(v)
#define pi pair<int, int>
#define vi vector<int>
using namespace std;
const int maxn = 1e5+3, SQ = 320;
const ll mod = 1e9+7;
ll n, x[maxn], d[maxn], dp[maxn], pf[maxn][SQ];

int main(){
    ios_base::sync_with_stdio(0); cin.tie(0);
    cin >> n;
    for(ll i = 1; i <= n; i++) cin >> d[i] >> x[i];
    dp[1] = 1;
    if(d[1] > SQ){
        for(ll j = 1+d[1]; j <= min(1+x[1]*d[1], n); j+=d[1]) dp[j] = (dp[j] + dp[1]) % mod;
    }
    else{
        pf[1][d[1]] = (pf[1][d[1]] + dp[1]) % mod;
        if(pf[1 + d[1] * (x[1] + 1)][d[1]] <= n) 
            pf[1 + d[1] * (x[1] + 1)][d[1]] = (pf[1 + d[1] * (x[1] + 1)][d[1]] - dp[1] + mod) % mod;
    }
    for(ll i = 2; i <= n; i++){
        for(ll j = 1; j <= SQ; j++) pf[i][j] = (pf[i][j] + pf[i-j][j]) % mod;
        for(ll j = 1; j <= SQ; j++) dp[i] = (dp[i] + pf[i][j]) % mod;
        if(d[i] > SQ){
            for(ll j = i+d[i]; j <= min(i+x[i]*d[i], n); j+=d[i]) dp[j] = (dp[j] + dp[i]) % mod;
        }
        else{
            pf[i][d[i]] = (pf[i][d[i]] + dp[i]) % mod;
            if(pf[i + d[i] * (x[i] + 1)][d[i]] <= n) 
                pf[i + d[i] * (x[i] + 1)][d[i]] = (pf[i + d[i] * (x[i] + 1)][d[i]] - dp[i] + mod) % mod;
        }
    }
    // for(int i = 1; i <= n; i++)
    //     for(int j = 1; j <= 10; j++) cout << pf[i][j] << " \n"[j==10];
    cout << accumulate(dp+1, dp+n+1, 0ll) % mod;
    return 0;
}

Compilation message (stderr)

Main.cpp: In function 'int main()':
Main.cpp:26:56: warning: iteration 319 invokes undefined behavior [-Waggressive-loop-optimizations]
   26 |         for(ll j = 1; j <= SQ; j++) pf[i][j] = (pf[i][j] + pf[i-j][j]) % mod;
      |                                                 ~~~~~~~^
Main.cpp:26:25: note: within this loop
   26 |         for(ll j = 1; j <= SQ; j++) pf[i][j] = (pf[i][j] + pf[i-j][j]) % mod;
      |                       ~~^~~~~
Main.cpp:27:61: warning: iteration 319 invokes undefined behavior [-Waggressive-loop-optimizations]
   27 |         for(ll j = 1; j <= SQ; j++) dp[i] = (dp[i] + pf[i][j]) % mod;
      |                                                      ~~~~~~~^
Main.cpp:27:25: note: within this loop
   27 |         for(ll j = 1; j <= SQ; j++) dp[i] = (dp[i] + pf[i][j]) % mod;
      |                       ~~^~~~~

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