Submission #54675

#	Time	Username	Problem	Language	Result	Execution time	Memory
54675		okaybody10	Mecho (IOI09_mecho)	C++98	100 / 100	242 ms	52292 KiB

mecho

#include <bits/stdc++.h>
using namespace std;
typedef pair<int,int> pii;
typedef pair<pii,int> piii;
int dx[4]={-1,0,1,0},dy[4]={0,1,0,-1};
int pre[2000][2000];
char mark[2000][2000];
int homex,homey;
int s,sx,sy,N;
bool test(int time)
{
    bool reach[2005][2005];
    memset(reach,0,sizeof(reach));
    if(time * s >= pre[sx][sy]) return false;
    queue<piii> q;
    q.push(make_pair(make_pair(sx,sy),time*s));
    reach[sx][sy]=1;
    while(!q.empty())
    {
        int x=q.front().first.first;
        int y=q.front().first.second;
        int dis=q.front().second;
        if(mark[x][y]=='D') return true;
        q.pop();
        for(int c=0;c<4;c++)
        {
            int cx=x+dx[c],cy=y+dy[c];
            if(cx<0 || cx>=N || cy<0 || cy>=N || pre[cx][cy]<=dis+1 || mark[cx][cy]=='T' || reach[cx][cy]) continue;
            reach[cx][cy]=true;
            q.push(make_pair(make_pair(cx,cy),dis+1));
        }
    }
    return false;
}
int main()
{
    memset(pre,-1,sizeof(pre));
    scanf("%d %d",&N,&s);
    queue<pii> que;
    for(int i=0;i<N;i++)scanf("%s",mark[i]);
    for(int i=0;i<N;i++){
            for(int j=0;j<N;j++)
            {
                if(mark[i][j]=='M') sx=i,sy=j,mark[i][j]='G';
                if(mark[i][j]=='D') homex=i,homey=j;
                if(mark[i][j]=='H') que.push(make_pair(i,j)),pre[i][j]=0;
            }
    }
    pre[homex][homey]=N*N*s;
    while(!que.empty())
    {
        int x=que.front().first;
        int y=que.front().second;
        int dis=pre[x][y];
        que.pop();
        for(int c=0;c<4;c++)
        {
            int cx=x+dx[c],cy=y+dy[c];
            if(cx<0 || cx>=N || cy<0 || cy>=N || pre[cx][cy]!=-1 || mark[cx][cy]!='G') continue;
            pre[cx][cy]=dis+s;
            que.push(make_pair(cx,cy));
        }
    }
    int low=0,high=N*N*2,ans=-1;
    for(;low<high;)
    {
        int mid=(low+high)/2;
        if(test(mid)) ans=max(ans,mid),low=mid+1;
        else high=mid;
    }
    return !printf("%d",ans);
}

Compilation message (stderr)

mecho.cpp: In function 'int main()':
mecho.cpp:38:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
     scanf("%d %d",&N,&s);
     ~~~~~^~~~~~~~~~~~~~~
mecho.cpp:40:30: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
     for(int i=0;i<N;i++)scanf("%s",mark[i]);
                         ~~~~~^~~~~~~~~~~~~~

• Subtask 1: 100 / 100