Submission #1266293

#TimeUsernameProblemLanguageResultExecution timeMemory
1266293herominhsteveTrains (BOI24_trains)C++20
21 / 100
188 ms2120 KiB
#include <bits/stdc++.h> #define el '\n' #define FNAME "trains" #define allof(x) x.begin(),x.end() #define allof1(x) x.begin()+1,x.end() #define mset(x,n) memset(x,(n),sizeof(x)) using namespace std; const long long MOD = (long long) 1e9+7; template<class X,class Y> bool minimize(X &a,Y b){ if (a>b) {a=b; return true;} return false;} template<class X,class Y> bool maximize(X &a,Y b){ if (a<b) {a=b; return true;} return false;} void setup(){ ios_base::sync_with_stdio(0); cin.tie(0);cout.tie(0); if (fopen(FNAME".inp","r")){ freopen(FNAME".inp","r",stdin); freopen(FNAME".out","w",stdout); } } struct Train{ long long d,x; int ID; Train(): d(0),x(0),ID(-1){} Train(long long D,long long X,int _ID): d(D), x(X),ID(_ID){} bool canTravel(int cID){ if (!d) return false; if (cID<=ID or ID==-1) return false; cID -= ID; if (cID % d) return false; return (cID/d <= x); } }; int n; vector<Train> a; void init(){ cin>>n; a.assign(n+1,Train()); for (int i=1;i<=n;i++){ cin>>a[i].d>>a[i].x; a[i].ID=i; } } inline void add(long long &x,long long y){ x+=y; if (x>=MOD) x-=MOD; } namespace BruteDP{ void solve(){ // ! dp[i]: # of ways to get to city i and ending at city i from city 1 vector<long long> dp(n+1,0); dp[1] = 1; for (int i=2;i<=n;i++){ for (int j=i-1;j>=1;j--){ if (a[j].canTravel(i)) add(dp[i],dp[j]); } } long long res = 0; for (int i=1;i<=n;i++) add(res,dp[i]); cout<<res; exit(0); } }; void sol(){ if (n<=1e4) BruteDP::solve(); } int main(){ setup(); init(); sol(); }

Compilation message (stderr)

Main.cpp: In function 'void setup()':
Main.cpp:16:24: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   16 |                 freopen(FNAME".inp","r",stdin);
      |                 ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~
Main.cpp:17:24: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   17 |                 freopen(FNAME".out","w",stdout);
      |                 ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
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