Submission #1100022

#	Time	Username	Problem	Language	Result	Execution time	Memory
1100022		asli_bg	Mecho (IOI09_mecho)	C++11	100 / 100	138 ms	3956 KiB

mecho

#pragma GCC optimize("O3,unroll-loops")

#include<bits/stdc++.h>
using namespace std;

#include <ext/pb_ds/assoc_container.hpp>
using namespace __gnu_pbds;
#define inset tree<int,null_type,less<int>,rb_tree_tag,tree_order_statistics_node_update>

//#define int long long

#define fi first
#define se second
#define all(x) x.begin(),x.end()
#define FOR(i,a) for(int i=0;i<(a);i++)
#define FORE(i,a,b) for(int i=(a);i<(b);i++)

typedef pair<int,int> pii;
typedef vector<int> vi;
typedef vector<bool> vb;
typedef vector<pii> vii;

#define cont(x) for(auto el:x) {cout<<el<<' ';} cout<<endl;
//#define endl '\n'
#define contp(x) for(auto el:x) {cout<<el.fi<<'-'<<el.se<<' ';} cout<<endl;
#define pb push_back

#define sp <<' '<<

#define DEBUG(x) {cout<<(#x) sp x<<endl;}

const int MAXN=805;
const int INF=1e9;

int n,s;
vector<string> grid;
int mark[MAXN][MAXN];

pii bas,son;
int yon1[4]={1,-1,0,0};
int yon2[4]={0,0,-1,1};
//sag, sol, asagi, yukari

bool isvalid(int x,int y,bool f){
    if(x>=n or y>=n or x<0 or y<0) return false;
    if(f){
        if(grid[x][y]!='G' and grid[x][y]!='M') return false;
        if(mark[x][y]) return false;
    }
    else{
        if(grid[x][y]!='G' and grid[x][y]!='D') return false;
    }
    return true;
}

bool check(int deg){
    //düz shortest path bfs
    vector<vb> vis(n+1, vb(n+1,false));
    queue<pair<pii,int>> q;

    if(mark[bas.fi][bas.se]<deg) return false;

    q.push({bas,0});
    vis[bas.fi][bas.se]=true;

    while(!q.empty()){
        auto el=q.front();
        q.pop();

        int adim=el.se;
        int x=el.fi.fi;
        int y=el.fi.se;

        FOR(i,4){
            int yenix=x+yon1[i];
            int yeniy=y+yon2[i];

            if(!isvalid(yenix,yeniy,false)) continue;
            if(vis[yenix][yeniy]) continue;
            
            int sure=adim/s;
            if(mark[yenix][yeniy]<deg+sure) continue;
            if((adim+1)%s==0){
                if(mark[yenix][yeniy]==deg+sure) continue;   
            }

            q.push({{yenix,yeniy},adim+1});
            vis[yenix][yeniy]=true;
        }
    }

    return vis[son.fi][son.se];
}

signed main(){
    ios_base::sync_with_stdio(0);
    cin.tie(0);

    cin>>n>>s;
    grid.resize(n);
    FOR(i,n) cin>>grid[i];
    queue<pii> q;

    int say=0;
    FOR(i,n){
        FOR(j,n){
            if(grid[i][j]=='H'){
                q.push({i,j});
                mark[i][j]=0;
            }
            else if(grid[i][j]=='M') {
                bas={i,j};
                say++;
            }
            else if(grid[i][j]=='D'){
                son={i,j};
                mark[i][j]=INF;
            }
            else say++;
        }
    }

    int mx=0;

    while(!q.empty()){
        auto el=q.front();
        q.pop();

        FOR(i,4){
            int yenix=el.fi+yon1[i];
            int yeniy=el.se+yon2[i];
            if(isvalid(yenix,yeniy,true)){
                mark[yenix][yeniy]=mark[el.fi][el.se]+1;
                mx=max(mx,mark[yenix][yeniy]);
                q.push({yenix,yeniy});
            }
        }
    }

    int l=0;
    int r=mx+1;
    while(l+1<r){
        int mid=(l+r)/2;
        if(check(mid)) l=mid;
        else r=mid;
    }

    cout<<l-1<<endl;
}

• Subtask 1: 100 / 100