Submission #335753

#	Time	Username	Problem	Language	Result	Execution time	Memory
335753		Christopher_Rdz	Mecho (IOI09_mecho)	C++14	100 / 100	256 ms	9196 KiB

mecho

#include <bits/stdc++.h>
using namespace std;
struct node{
    int i;
    int j;
    node(){}
    node(int I,int J){
        i=I;
        j=J;
    }
};
queue<node> Q;
char forest[805][805];
int bees[805][805];
int dist[805][805];
int energy[805][805];
int dx[4]={1,-1,0,0};
int dy[4]={0,0,1,-1};
int n,s;

void bfsBees(){    for (int i = 1; i <= n; i++){        for (int j = 1; j <= n; j++){            bees[i][j]=INT_MAX;
            if(forest[i][j]=='H'){
                Q.push(node(i,j));
                bees[i][j]=0;            }       }    }
    while(!Q.empty()){
        node u=Q.front();
        Q.pop();
        for(int mov=0;mov<4;mov++){
            int i=u.i+dx[mov];
            int j=u.j+dy[mov];
            if(i<1 || i>n) continue;
            if(j<1 || j>n) continue;
            if(forest[i][j]=='T' || forest[i][j]=='D') continue;
            if(bees[i][j]==INT_MAX){
                bees[i][j]=bees[u.i][u.j]+1;
                Q.push(node(i,j));
            }
        }
    }
}

node mecho;
node home;

bool bfsMecho(int init){    for (int i = 1; i <= n; i++){        for (int j = 1; j <= n; j++){            dist[i][j]=INT_MAX;
            energy[i][j]=0;        }}
    if(bees[mecho.i][mecho.j]<=init) return false;
    dist[mecho.i][mecho.j]=init;
    energy[mecho.i][mecho.j]=0;
    Q.push(mecho);
    while(!Q.empty()){
        node u=Q.front();
        Q.pop();
        if(bees[u.i][u.j]==dist[u.i][u.j] && energy[u.i][u.j]==0) continue;
        for(int mov=0;mov<4;mov++){
            int i=u.i+dx[mov];
            int j=u.j+dy[mov];
            if(i<1 || i>n) continue;
            if(j<1 || j>n) continue;
            if(forest[i][j]=='T') continue;
            if(dist[i][j]==INT_MAX){
                int change=(energy[u.i][u.j]>0)? 0 : 1;
                dist[i][j]=dist[u.i][u.j]+change;
                if(bees[i][j]<dist[i][j]) continue;
                energy[i][j]=(energy[u.i][u.j]>0)? energy[u.i][u.j]-1 : s-1;
                Q.push(node(i,j));
            }
        }
    }
    return dist[home.i][home.j]!=INT_MAX;
}

int binarySearch(){
    int k=-1;
    int L=0,R=3*n;
    while(L<R){
        int mid=(L+R)/2;
        if(bfsMecho(mid)){
            k=mid;
            L=mid+1;
        }
        else{
            R=mid;
        }
    }
    return k;
}

int binarySearch2(){
    int k=-1;
    for(int b=5000;b>=1;b/=2){
        while(bfsMecho(b+k)) k+=b;
    }
    return k;
}

int main()
{
    ios_base::sync_with_stdio(0);cin.tie(0);
    cin>>n>>s;
    for(int i=1;i<=n;i++){
        for(int j=1;j<=n;j++){
            cin>>forest[i][j];
            if(forest[i][j]=='M'){
                mecho=node(i,j);
            }
            else if(forest[i][j]=='D'){
                home=node(i,j);
            }
        }
    }        
    bfsBees();
    int ans=binarySearch2();
    cout<<ans<<endl;
    return 0;
}

• Subtask 1: 100 / 100