Submission #490089

#	Time	Username	Problem	Language	Result	Execution time	Memory
490089		keertan	Tracks in the Snow (BOI13_tracks)	C++17	77.50 / 100	536 ms	123920 KiB

tracks

/**
 * If you live in imaginary world when your imaginary situation encounter in 
 * real situation you can't enjoiy it because you have to do pending work.
 * {This pending work appeared because you wasted that time for your useless
 * imagianry thinking .}
 */
#include<bits/stdc++.h>
using namespace std;
//#define int  int64_t
#define all(x) x.begin(),x.end()
#define all1(x) x.rbegin(),x.rend()
#define sz(x) (int)(x.size())
const int N=4e5+5,mod=1e9+7;

void solve(){
	int n,m;
	cin>>n>>m;
	vector<string> z(n);
	for (string &it:z){cin>>it;}
	int ans=0;
	deque<pair<int,int>> q;
	vector<vector<int>> dis(n,vector<int>(n));
	dis[0][0]=1;
	q.emplace_back(0,0);
	vector<int> dx{1,-1,0,0},dy{0,0,1,-1};
	while(!q.empty()){
		pair<int,int> u=q.front();
		q.pop_front();
		ans=max(ans,dis[u.first][u.second]);
		for (int i=0;i<4;i++){
			int x=u.first+dx[i],y=u.second+dy[i];
			if (min(x,y)>=0 && x<n && y<m && z[x][y]!='.' && dis[x][y]==0){
				if (z[u.first][u.second]==z[x][y]){
					q.emplace_front(x,y);
					dis[x][y]=dis[u.first][u.second];
				}
				else{
					q.emplace_back(x,y);
					dis[x][y]=dis[u.first][u.second]+1;
				}
			}
		}
	}
	cout<<ans;
}
int32_t main(){
    ios::sync_with_stdio(false);cin.tie(nullptr);cout.tie(nullptr);
    int tq=1;
    //cin>>tq;
    for (;tq;tq--){solve();}
}
//is a bruteforce possible?
//think greedier, make more assumptions
// if we you find solution using loop to decrease complexity use bs
//stuck for more than 5 minutes? move on  

• Subtask 1: 25 / 30
• Subtask 2: 52.5 / 70