Submission #1304560

#	Time	Username	Problem	Language	Result	Execution time	Memory
1304560		crispxx	Tracks in the Snow (BOI13_tracks)	C++20	100 / 100	608 ms	112216 KiB

tracks

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

using ll = long long;

const int inf = 1e9;

void solve() {
	int n, m; cin >> n >> m;
	
	vector<string> s(n);
	
	for(auto &str : s) cin >> str;
	
	vector d(n, vector(m, inf));
	
	d[0][0] = 1;
	
	deque<array<int, 2>> q;
	
	q.push_back({0, 0});
	
	int dx[4] = {1, -1, 0, 0};
	int dy[4] = {0, 0, 1, -1};
	
	int ans = 0;
	
	while(!q.empty()) {
		auto [x, y] = q.front();
		q.pop_front();
		
		ans = max(ans, d[x][y]);
		
		for(int i = 0; i < 4; i++) {
			int nx = x + dx[i], ny = y + dy[i];
			if(nx < 0 || ny < 0 || nx >= n || ny >= m || s[nx][ny] == '.') continue;
			if(s[x][y] == s[nx][ny]) {
				if(d[nx][ny] > d[x][y]) {
					d[nx][ny] = d[x][y];
					q.push_front({nx, ny});
				}
			} else {
				if(d[nx][ny] > d[x][y] + 1) {
					d[nx][ny] = d[x][y] + 1;
					q.push_back({nx, ny});
				}
			}
		}
	}
	
	cout << ans << '\n';
}

signed main() {
	ios::sync_with_stdio(false);
	cin.tie(nullptr);
	
	solve();
}

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