Submission #658881

#	Time	Username	Problem	Language	Result	Execution time	Memory
658881		ansgar	Tracks in the Snow (BOI13_tracks)	C++17	100 / 100	571 ms	235728 KiB

tracks

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

#define int long long
#define vi vector<int>
#define vvi vector<vi>
#define pii pair<int,int>
#define vpii vector<pii>
#define vvpii vector<vpii>
#define vb vector<bool>
#define vc vector<char>
#define vvc vector<vc>
#define vvb vector<vb>
#define si set<int>
#define mii map<int,int>

const int mod=1e9+7;
const int N=2e5+1;
const int LN=LLONG_MAX/10;
int dx[4]{1,-1,0,0},dy[4]{0,0,1,-1};
int n,m,depth[4000][4000],ans=1;
string snow[4000];
bool inside(int x,int y){
    return (x>-1 and x<n and y>-1 and y<m and snow[x][y]!='.');
}
signed main(){
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);
    cin>>n>>m;
    for(int i=0;i<n;i++)cin>>snow[i];
    deque<pii> Q;
    Q.push_back({0,0});
    depth[0][0]=1;
    while(Q.size()){
        pii c=Q.front();
        Q.pop_front();
        ans=max(ans,depth[c.first][c.second]);
        for(int i=0;i<4;i++){
            int x=c.first+dx[i],y=c.second+dy[i];
            if(inside(x,y) and depth[x][y]==0){
                if(snow[x][y]==snow[c.first][c.second]){
                    depth[x][y]=depth[c.first][c.second];
                    Q.push_front({x,y});
                }
                else{
                    depth[x][y]=depth[c.first][c.second]+1;
                    Q.push_back({x,y});
                }
            }
        }
    }
    cout<<ans;
}

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