| # | Submission time | Handle | Problem | Language | Result | Execution time | Memory |
|---|---|---|---|---|---|---|---|
| 876211 | 2023-11-21T12:43:52 Z | vjudge1 | Tracks in the Snow (BOI13_tracks) | C++17 | 0 ms | 0 KB |
#pragma GCC optimize("Ofast")
#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define ld long double
#define pb push_back //emplace_back
#define pp pop_back
#define pii pair<ll, ll> //pair<int, int>
#define all(x) (x).begin(),(x).end()
#define mp(a,b) make_pair(a , b)
#define lb lower_bound
#define ub upper_bound
#define sz(x) (ll)(x).size()
#define F first
#define S second
#define bg(x) (x).begin()
#define For(x, n) for(int (x) = 0 ; (x) < (n) ; (x)++)
#define debug(x) cout << #x << " : " << x << endl
#define endl (char)(10)
#define arr(x) array<int , (x)>
#define yes cout << "YES" << endl
#define no cout << "NO" << endl
#define FAST ios_base::sync_with_stdio(0);cin.tie(0);
ll Sum(ll a , ll b , ll MOD)
{
a %= MOD;
b %= MOD;
a += b;
return a % MOD;
}
ll Mul(ll a , ll b , ll MOD)
{
a %= MOD;
b %= MOD;
a *= b;
return a % MOD;
}
ll Pow(ll a , ll b , ll MOD)
{
ll res = 1;
while(b)
{
if((b & 1))res = Mul(res , a , MOD);
a = Mul(a , a , MOD);
b >>= 1;
}
return res;
}
ll Min(ll a , ll b)
{
if(a > b)return b;
return a;
}
ll Max(ll a , ll b)
{
if(a > b)return a;
return b;
}
ll Ceil(ll a , ll b)
{
if(a % b)return (a/b)+1;
return a/b;
}
/////////////////////
//VALS
const ll maxn = 4009;
ll n,m;
string s[maxn];
bool vis[maxn][maxn];
ll ans;
ll x[4] = {1,-1,0,0};
ll y[4] = {0,0,1,-1};
/////////////////////
//FUNCTIONS
void bfs(queue<pii> q1 = {mp(0,0)}, queue<pii> q2 = {}, ll d = 1)
{
if(q1.empty())return;
ans = d;
while(!q1.empty())
{
pii p = q1.front();
q1.pop();
//debug(p.F);
//debug(p.S);
For(i,4)
{
if(p.F + x[i] < 0 or p.F + x[i] >= n or p.S + y[i] < 0 or p.S + y[i] >= m or s[p.F + x[i]][p.S + y[i]] == '.' or vis[p.F + x[i]][p.S + y[i]] == 1)continue;
vis[p.F + x[i]][p.S + y[i]] = 1;
bool flag = (s[p.F + x[i]][p.S + y[i]] == s[p.F][p.S]);
//debug(i);
//debug(flag);
if(flag)
q1.push(mp(p.F + x[i], p.S + y[i]));
else
q2.push(mp(p.F + x[i], p.S + y[i]));
}
}
bfs(q2, q1, d+1);
}
/////////////////////
//SOLVE
void solve()
{
cin >> n >> m;
For(i,n)cin >> s[i];
vis[0][0] = 1;
bfs();
cout << ans << endl;
}
/////////////////////
//MAIN
int main()
{
FAST;
ll t = 1;
// cin >> t;
while(t--)
{
solve();
}
}
/////////////////////
/*
ZZZZZZZ A M M IIIIIII N N
Z A A M M M M I NN N
Z A A M M M M I N N N
Z AAAAAAA M M M I N N N
Z A A M M I N N N
Z A A M M I N NN
ZZZZZZZ A A M M IIIIIII N N TREE
*/