Submission #1289533

#	Time	Username	Problem	Language	Result	Execution time	Memory
1289533		muhammad-ahmad	Tracks in the Snow (BOI13_tracks)	C++20	100 / 100	808 ms	236244 KiB

tracks

// #include <bits/stdc++.h>
#include <iostream>
#include <cmath>
#include <algorithm>
#include <map>
#include <vector>
#include <iomanip>
#include <string>
#include <queue>
#include <set>
#include <deque>
#include <numeric>
#include <stack>
#include <chrono>
using namespace std;

#define int long long
#define endl '\n'
#define all(v) (v).begin(), (v).end()
#define rall(v) (v).rbegin(), (v).rend()
#define fi first
#define se second

const int N = 4005;
int n, m, dist[N][N];
bool vis[N][N];
string s[N];
vector<int> dx = {0, 0, 1, -1}, dy = {1, -1, 0, 0};

bool check(int x, int y){
	return (x > 0 && x <= n && y > 0 && y <= m && !vis[x][y] && s[x][y] != '.');
}

signed bfs(){
	deque<pair<int, int>> q;
	q.push_back({1, 1});
	vis[1][1] = 1;
	int ma = 0;
	while (q.size()){
		auto [x, y] = q.front(); q.pop_front();
		
		ma = max(ma, dist[x][y]);
		
		for (int j = 0; j < 4; j++){
			int ddx = dx[j], ddy = dy[j];
			int cx = x + ddx, cy = y + ddy;
			if (check(cx, cy) && s[cx][cy] == s[x][y]){
				dist[cx][cy] = dist[x][y];
				q.push_front({cx, cy});
				vis[cx][cy] = 1;
			}
			else if (check(cx, cy)){
				dist[cx][cy] = dist[x][y] + 1;
				q.push_back({cx, cy});
				vis[cx][cy] = 1;
			}
		}

	}
	
	return ma;
}

void solve() {
	cin >> n >> m;
	for (int i = 1; i <= n; i++){
		cin >> s[i];
		s[i] = "." + s[i];
	}
	
	for (int i = 1; i <= n; i++){
		for (int j = 1; j <= m; j++) dist[i][j] = 1e18;
	}
	
	dist[1][1] = 1;
	cout << bfs() << endl;
	return;
}

signed main() {
    srand(chrono::steady_clock::now().time_since_epoch().count());
    int tc = 1;
    // cin >> tc;
    while (tc--) solve();
    return 0;
}

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