Submission #575987

#	Time	Username	Problem	Language	Result	Execution time	Memory
575987		OnionEgg	Tracks in the Snow (BOI13_tracks)	C++17	100 / 100	594 ms	231780 KiB

tracks

#pragma GCC optimize("O3")
#pragma GCC optimize("unroll-loops")
#pragma GCC target("avx2")
#include<bits/stdc++.h>
#define ll long long
#define fas ios::sync_with_stdio(0); cout.tie(0); cin.tie(0)
#define el "\n"
#define fi first	
#define se second
#define th third
#define taskName "codefuck"
using namespace std;
const ll mod = 1e9+7;
ll dx[4] = {1, -1, 0, 0}, dy[4] = {0, 0, 1, -1};
ll n, m, depth[4005][4005], res;
string snow[4000];
bool inside(ll x, ll y)
{
	return (x > -1 && x < n && y > -1 && y < m && snow[x][y] != '.');
}
void solve()
{
	cin >> n >> m;
	for(int i = 0; i < n; i++) cin >> snow[i];
	deque<pair<ll, ll>>q;
	q.push_back({0, 0});
	depth[0][0] = 1;
	res = 1;
	while(q.size())
	{
		pair<ll, ll> c = q.front();
		q.pop_front();
		res = max(res, depth[c.fi][c.se]);
		for(int i = 0; i < 4; i++)
		{
			ll x = c.fi + dx[i], y = c.se + dy[i];
			if(inside(x, y) && depth[x][y] == 0)
			{
				if(snow[x][y] == snow[c.fi][c.se])
				{
					depth[x][y] = depth[c.fi][c.se];
					q.push_front({x, y});
				}
				else
				{
					depth[x][y] = depth[c.fi][c.se] + 1;
					q.push_back({x, y});
				}
			}
		}
	}
	cout << res;
}																	
int main()
{
	fas;
    if (fopen(taskName".inp", "r"))
    {
        freopen(taskName".inp", "r", stdin);
        freopen(taskName".out", "w", stdout);
    }
    ll testcase = 1;
	//cin >> testcase;
	while(testcase--)
	{
		solve();
	}
}

Compilation message (stderr)

tracks.cpp: In function 'int main()':
tracks.cpp:59:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   59 |         freopen(taskName".inp", "r", stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~
tracks.cpp:60:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   60 |         freopen(taskName".out", "w", stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~

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