Submission #892978

#	Time	Username	Problem	Language	Result	Execution time	Memory
892978		ilef	Mecho (IOI09_mecho)	C++14	95 / 100	180 ms	25688 KiB

mecho

#include<bits/stdc++.h>
#define int long long 
using namespace std;
const int inf=INT_MAX;
 int n,s;
 bool safe(int i,int j){
     return i>=0 && i<n && j>=0 && j<n;
 }
 int di[4]={0,0,-1,1};
 int dj[4]={1,-1,0,0};
int32_t main(){
    ios_base::sync_with_stdio(false);
    cin.tie(0);
    cout.tie(0);
  
    cin>>n>>s;
    char mat[n][n];
    int dist1[n][n];
    int dist2[n][n];
    int homex,homey;
    int honx,hony;
    queue<pair<int,int>>q;
    bool vis1[n][n];
    bool vis2[n][n];
    for(int i=0;i<n;i++){
        for(int j=0;j<n;j++){
            vis1[i][j]=false;
            vis2[i][j]=false;
            dist1[i][j]=inf;
            dist2[i][j]=inf;
        }
    }
    for(int i=0;i<n;i++){
        for(int j=0;j<n;j++){
            cin>>mat[i][j];
            if(mat[i][j]=='M'){
                honx=i;
                hony=j;
            }
            if(mat[i][j]=='D'){
                homex=i;
                homey=j;
            }
            if(mat[i][j]=='H'){
                q.push({i,j});
                dist1[i][j]=0;
                vis1[i][j]=true;
            }
        }
    }
    while(!q.empty()){
        const auto &[i,j]=q.front();
        q.pop();
        for(int l=0;l<4;l++){
            int x=i+di[l];
            int y=j+dj[l];
            if(safe(x,y) && !vis1[x][y] && (mat[x][y]=='G'||mat[x][y]=='M')){
                dist1[x][y]=dist1[i][j]+1;
                vis1[x][y]=true;
                q.push({x,y});
            }
        }
    }
    //bool reached=false;
    int ll=0,rr=n*n;
    int ans=-1;
    while(ll<=rr){
        int mid=(ll+rr)/2;
          for(int i=0;i<n;i++){
          for(int j=0;j<n;j++){
            vis2[i][j]=false;
             dist2[i][j]=inf;
            
        }
    }
       
        if(mid<dist1[honx][hony]){
            dist2[honx][hony]=0;
            vis2[honx][hony]=true;
            q.push({honx,hony});
        }
        while(!q.empty()){
        const auto &[i,j]=q.front();
        q.pop();
        for(int l=0;l<4;l++){
            int x=i+di[l];
            int y=j+dj[l];
                    if(safe(x,y) && (mat[x][y]=='G'|| mat[x][y]=='M')&& !vis2[x][y] &&((dist2[i][j]+1)/s<(dist1[x][y]-mid))){
                        dist2[x][y]=dist2[i][j]+1;
                        vis2[x][y]=true;
                        q.push({x,y});
                    }
                }
             
                }
    bool reached=false;
    for(int i=0;i<4;i++){
        int x=homex+di[i];
        int y=homey+dj[i];
          
        if(safe(x,y) && vis2[x][y]  && (mat[x][y]=='G'|| mat[x][y]=='M') && dist2[x][y]/s<dist1[x][y]-mid){
            reached=true;
        }
    }
            
    if(reached){
        ans=mid;
        ll=mid+1;
    }
    else{
        //ans=mid;
        rr=mid-1;
    }
    }
       cout<<ll-1<<endl;
}

Compilation message (stderr)

mecho.cpp: In function 'int32_t main()':
mecho.cpp:52:21: warning: structured bindings only available with '-std=c++17' or '-std=gnu++17'
   52 |         const auto &[i,j]=q.front();
      |                     ^
mecho.cpp:83:21: warning: structured bindings only available with '-std=c++17' or '-std=gnu++17'
   83 |         const auto &[i,j]=q.front();
      |                     ^
mecho.cpp:66:9: warning: variable 'ans' set but not used [-Wunused-but-set-variable]
   66 |     int ans=-1;
      |         ^~~
mecho.cpp:78:30: warning: 'hony' may be used uninitialized in this function [-Wmaybe-uninitialized]
   78 |             dist2[honx][hony]=0;
      |             ~~~~~~~~~~~~~~~~~^~
mecho.cpp:99:13: warning: 'homey' may be used uninitialized in this function [-Wmaybe-uninitialized]
   99 |         int y=homey+dj[i];
      |             ^
mecho.cpp:98:13: warning: 'homex' may be used uninitialized in this function [-Wmaybe-uninitialized]
   98 |         int x=homex+di[i];
      |             ^
mecho.cpp:78:30: warning: 'honx' may be used uninitialized in this function [-Wmaybe-uninitialized]
   78 |             dist2[honx][hony]=0;
      |             ~~~~~~~~~~~~~~~~~^~

• Subtask 1: 95 / 100