Submission #923893

#	Time	Username	Problem	Language	Result	Execution time	Memory
923893		Aiperiii	Tracks in the Snow (BOI13_tracks)	C++14	38.75 / 100	2090 ms	157636 KiB

tracks

#include <bits/stdc++.h>
#define int long long
#define ff first
#define ss second
#define pb push_back
#define all(x) x.begin(),x.end()
using namespace std;
const int N=4e3+5;
char a[N][N];
int path[N][N];
int h,w;

bool ok(char c){
   vector <int> x={1,-1,0,0};
   vector <int> y={0,0,1,-1};
   queue <pair <int,int> > q;
   q.push({0,0});
   if(a[0][0]==c or a[0][0]=='*'){
      path[0][0]=1;
      while(!q.empty()){
         int X=q.front().ff;
         int Y=q.front().ss;
         q.pop();
         for(int i=0;i<4;i++){
            if(X+x[i]>=0 && X+x[i]<h && Y+y[i]>=0 && Y+y[i]<w){
               if((a[X+x[i]][Y+y[i]]==c or a[X+x[i]][Y+y[i]]=='*') && !path[X+x[i]][Y+y[i]]){
                  path[X+x[i]][Y+y[i]]=1;
                  q.push({X+x[i],Y+y[i]});
               }
            }
         }
      }
   }
   if(path[h-1][w-1]){
      bool fg=0;
      for(int i=0;i<h;i++){
         for(int j=0;j<w;j++){
            if(path[i][j]){
               if(a[i][j]=='R' or a[i][j]=='F')fg=1;
               a[i][j]='*';
            }
            path[i][j]=0;
         }
      }
      if(fg)return true;
      else return false;
   }
   return false;
}
signed main(){
   ios_base::sync_with_stdio();
   cin.tie(0);cout.tie(0);
   
   cin>>h>>w;
   for(int i=0;i<h;i++){
      for(int j=0;j<w;j++){
         cin>>a[i][j];
      }
   }
   
   int ans=0;
   while(true){
      int cnt=0;
      for(int i=0;i<h;i++){
         for(int j=0;j<w;j++){
            if(a[i][j]=='.' or a[i][j]=='*')cnt++;
         }
      }
      if(cnt==h*w)break;
      if(ok('F'))ans++;
      else if(ok('R'))ans++;
   }
   cout<<ans<<"\n";
}

/*
FFR.....
.FRRR...
.FFFFF..
..RRRFFR
.....FFF
 */

• Subtask 1: 30 / 30
• Subtask 2: 8.75 / 70