Submission #542377

#	Time	Username	Problem	Language	Result	Execution time	Memory
542377		Tam_theguide	Tracks in the Snow (BOI13_tracks)	C++14	100 / 100	1597 ms	165212 KiB

tracks

#include <bits/stdc++.h>
using namespace std;
int n, m;
const int dx[4]={0, 0, 1, -1};
const int dy[4]={1, -1, 0, 0};
char a[4005][4005];
bool visited[4005][4005];
int d[4005][4005];
int ans=1;
using P=pair<pair<int, int>, int>;
deque<P>dq;
bool check(int i, int j){
    if (a[i][j]!='.' && 1<=i && i<=n && 1<=j && j<=m) return true;
    else return false;
}
void bfs(){
    dq.push_back({{1, 1}, 0});
    d[1][1]=1;//vi ton 1 con vat;
    while (!dq.empty()){
        int distance=dq.front().second;
        int u=dq.front().first.first;
        int v=dq.front().first.second;
        dq.pop_front();
        if (visited[u][v]) continue;
        visited[u][v]=true;
        ans=max(ans, distance);
        for (int t=0; t<4; t++){
            int ii=u+dx[t];
            int jj=v+dy[t];
            if (check(ii, jj)==false || visited[ii][jj]) continue;
            if (a[u][v]!=a[ii][jj]){
                if (d[u][v]+1<d[ii][jj]){
                    d[ii][jj]=d[u][v]+1;
                    dq.push_back({{ii, jj}, d[ii][jj]});
                }
            }else{
                if (d[u][v]<d[ii][jj]){
                    d[ii][jj]=d[u][v];
                    dq.push_front({{ii, jj}, d[ii][jj]});
                }
            }
        }
    }
    cout<<ans;
}
int main(){
    cin>>n>>m;
    for (int i=1;i <=n; i++){
        for (int j=1; j<=m; j++){
            cin>>a[i][j];
            if (i==1 && j==1) d[i][j]=1;
            else d[i][j]=1e9;
        }
    }
    bfs();
}

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