Submission #989584

#	Time	Username	Problem	Language	Result	Execution time	Memory
989584		Nurislam	Tracks in the Snow (BOI13_tracks)	C++17	100 / 100	594 ms	256600 KiB

tracks

///*                                                    __                    __                        __                    */
///*        ======     _      /| /|  __   _            /   |  |   /|  |   *  |    |  |  | /   /| |\  | /   |  |  * | /        */
///* \-       ||  |_| |_     / |/ | |  | |_  |-        |   |--|  /-|  |   |  \ \  |==|  |-   /=| | \ | |   |--|  | |-         */
///*          ||  | | |_    /     | |__|  _| |_        \__ |  | /  |  |__ |  __|  |  |  | \ /  | |  \| \__ |  |  | | \        */
///* 
// autor :: Rick Prime
#include <bits/stdc++.h>
using namespace std;
#include <ext/pb_ds/assoc_container.hpp> 
#include <ext/pb_ds/tree_policy.hpp> 
using namespace __gnu_pbds; 
  
#define ordered_set tree<int, null_type,less<int>, rb_tree_tag,tree_order_statistics_node_update> 

#define pb push_back
#define ff first
#define ss second
#define all(x) x.begin(),x.end()
#define rall(x) x.rbegin(),x.rend()
#define int long long
#define Mp make_pair
typedef vector<int> vi;
typedef vector<double> vd;
typedef pair<int,int> pii;
typedef vector<pii> vii;
const int N = 1e6, inf = 2e18, mod = 1e9+7;

void solve(){
	//freopen("snakes.in", "r", stdin);
	//freopen("snakes.out", "w", stdout );
	int h, w;
	cin >> h >> w;
	char a[h][w];
	for(int i = 0; i < h; i++){
		for(int j = 0; j < w; j++){
			cin >> a[i][j];
		}
	}
	deque<pair<int, pii> > q;
	q.pb({1,{0, 0}});
	vi di = {-1, 1, 0, 0};
	vi dj = {0, 0, -1, 1};
	int ans = 1, cnt = 0;
	int us[h][w]{};
	us[0][0] = 1;
	while(!q.empty()){
		auto [dis, ps] = q.front();
		auto [x, y] = ps;
		q.pop_front();
		ans = max(ans, dis);
		//cout << dis << ' ' << ++cnt << '\n';
		for(int k = 0; k < 4; k++){
			int nx = x + di[k];
			int ny = y + dj[k];
			if(nx<0 || ny<0 || nx>=h || ny>=w || a[nx][ny] == '.')continue;
			if(us[nx][ny])continue;
			us[nx][ny] = 1;
			if(a[nx][ny] == a[x][y])q.push_front({dis, {nx, ny}});
			else q.pb({dis+1,{nx,ny}});
		}
	}
	cout << ans << '\n';
}
 
 
 
signed main(){
	ios_base::sync_with_stdio(false);cin.tie(nullptr);cout.tie(nullptr);
	int test = 1;
	//cin >> test;
	while(test--){
		solve();
	}
}
 
 
 
 
 
 
 
 
 
 
 
 
 

Compilation message (stderr)

tracks.cpp: In function 'void solve()':
tracks.cpp:43:15: warning: unused variable 'cnt' [-Wunused-variable]
   43 |  int ans = 1, cnt = 0;
      |               ^~~

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