Submission #1187274

#	Time	Username	Problem	Language	Result	Execution time	Memory
1187274		pxsit	Tracks in the Snow (BOI13_tracks)	C++20	100 / 100	416 ms	89616 KiB

tracks

#include <bits/stdc++.h>
using namespace std;
int main(){
    ios::sync_with_stdio(false);
    cin.tie(NULL);
    int h,w;
    cin>>h>>w;
    vector<string> g(h);
    for(int i=0;i<h;i++) cin>>g[i];
    int n=h*w;
    const int INF=1e9;
    vector<int> dist(n,INF);
    deque<int> dq;
    dist[0]=0;
    dq.push_front(0);
    int dr[4]={-1,1,0,0}, dc[4]={0,0,-1,1};
    while(!dq.empty()){
        int id=dq.front(); dq.pop_front();
        int d=dist[id];
        int r=id/w, c=id%w;
        for(int k=0;k<4;k++){
            int nr=r+dr[k], nc=c+dc[k];
            if(nr<0||nr>=h||nc<0||nc>=w) continue;
            if(g[nr][nc]=='.') continue;
            int nid=nr*w+nc;
            int w1 = g[nr][nc]!=g[r][c];
            if(dist[nid]>d+w1){
                dist[nid]=d+w1;
                if(w1==0) dq.push_front(nid);
                else dq.push_back(nid);
            }
        }
    }
    int mx=0;
    for(int i=0;i<h;i++)
        for(int j=0;j<w;j++)
            if(g[i][j]!='.')
                mx=max(mx,dist[i*w+j]);
    cout<<mx+1;
    return 0;
}

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