Submission #382607

#	Time	Username	Problem	Language	Result	Execution time	Memory
382607		ritul_kr_singh	Tracks in the Snow (BOI13_tracks)	C++17	73.75 / 100	2145 ms	643052 KiB

tracks

#include <bits/stdc++.h>
using namespace std;
#define int long long
#define sp << " " <<
#define nl << "\n"

vector<int> e;
int find(int u){
	return e[u] < 0 ? u : e[u] = find(e[u]);
}
void unite(int u, int v){
	u = find(u), v = find(v);
	if(u==v) return;
	if(e[u] > e[v]) swap(u, v);
	e[u] += e[v], e[v] = u;
}

int dx[4] = {-1, 1, 0, 0};
int dy[4] = {0, 0, -1, 1};

signed main(){
	cin.tie(0)->sync_with_stdio(0);
	int h, w; cin >> h >> w;
	int g[h][w];
	bool vis[h*w];
	fill(vis, vis+h*w, false);
	e.assign(h*w, -1);
	queue<array<int, 3>> q;
	for(int i=0; i<h; ++i){
		for(int j=0; j<w; ++j){
			char c; cin >> c;
			if(c=='.') g[i][j] = 0;
			if(c=='F') g[i][j] = 1;
			if(c=='R') g[i][j] = 2;
			if(i and g[i-1][j]==g[i][j]) unite(i*w + j, i*w + j - w);
			if(j and g[i][j-1]==g[i][j]) unite(i*w + j, i*w + j - 1);
		}
	}
	map<int, vector<pair<int, int>>> group;
	for(int i=0; i<h; ++i){
		for(int j=0; j<w; ++j){
			if(g[i][j]) group[find(i*w + j)].emplace_back(i, j);
		}
	}
	set<int> curr, prev;
	curr.insert(find(0));
	vis[find(0)] = true;
	int ans = 0;
	while(!curr.empty()){
		++ans;
		for(int currGroup : curr){
			for(auto s : group[currGroup]){
				for(int k=0; k<4; ++k){
					int i = s.first + dx[k], j = s.second + dy[k];
					if(i<0 or j<0 or i==h or j==w or !g[i][j] or vis[find(i*w + j)]) continue;
					prev.insert(find(i*w + j));
					vis[find(i*w + j)] = true;
				}
			}
		}
		curr.clear();
		swap(curr, prev);
	}
	cout << ans;
}

• Subtask 1: 30 / 30
• Subtask 2: 43.75 / 70