Submission #1295214

#	Time	Username	Problem	Language	Result	Execution time	Memory
1295214		darkdevilvaqif	Tracks in the Snow (BOI13_tracks)	C++20	100 / 100	567 ms	64180 KiB

tracks

#pragma GCC optimize("O3")
#pragma GCC optimize ("unroll-loops")
// #pragma GCC target("avx2")
#include <bits/stdc++.h>
#define ll long long
#define ull unsigned ll
#define ld long double
#define all(v, l) v.begin() + l, v.end()
#define rall(v, l) v.rbegin(), v.rend() - l
#define pb push_back
#define pf push_front
#define rsz resize
#define fi first
#define se second
#define LMAX LLONG_MAX
#define LMIN LLONG_MIN
#define IMAX INT_MAX
#define IMIN INT_MIN
#define endl "\n"
#define newline cout << endl;
using namespace std;
 
// structs
struct graph
{
    vector <vector <char> > g;
    vector <vector <bool> > used;
    
    int N, M;
    void prep()
    {
        g.rsz(N + 1);
        used.rsz(N + 1);
        for (int i = 0; i <= N; i++)
        {
            g[i].rsz(M + 1);
            used[i].rsz(M + 1);
        }
    }
    
    void get()
    {
        for (int i = 1; i <= N; i++)
        {
            for (int j = 1; j <= M; j++)
            {
                cin >> g[i][j];
            }
        }
    }
    
    bool check(int r, int c)
    {
        return !(r < 1 || r > N || c < 1 || c > M || used[r][c] || g[r][c] == '.');
    }
    
    int BFS(pair <int, int> start)
    {
        int cnt = 0; 
        deque <pair <int, int> > dq;
        dq.pb(start);
        used[start.fi][start.se] = true;
        char curr = 'X';
        
        while (!dq.empty())
        {
            auto [r, c] = dq.front();
            cnt += curr != g[r][c];
            curr = g[r][c];
            dq.pop_front();
            
            for (auto [gotor, gotoc] : vector <pair <int, int> > {{r + 1, c}, {r - 1, c}, {r, c + 1}, {r, c - 1}})
            {
                if (!check(gotor, gotoc))
                {
                    continue;
                }
                
                used[gotor][gotoc] = true;
                if (g[gotor][gotoc] == g[r][c])
                {
                    dq.pf({gotor, gotoc});
                }
                else
                {
                    dq.pb({gotor, gotoc});
                }
            }
        }
        
        return cnt;
    }
    
    void cleanse()
    {
        for (int i = 0; i <= N; i++)
        {
            fill(all(used[i], 0), false);
        }
    }
};

// globals

// variables

// iterators
int i;

// notes
/*
 -stuff you should look for-
* int overflow, array bounds
* special cases (n=1?)
* do something instead of nothing and stay organized
* WRITE STUFF DOWN
* DON'T GET STUCK ON ONE APPROACH

continue - skip the rest in the loop
*/

// functions
ll GCD(ll numeroune, ll numerodeux);
ll LCM(ll numeroune, ll numerodeux);
ll power(ll numeroune, ll numerodeux);
 
void solve()
{
    graph G;
    cin >> G.N >> G.M;
    G.prep();
    G.get();
    
    G.cleanse();
    
    cout << G.BFS({1, 1});
}
 
int main()
{
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    int t = 1;
    // cin >> t;
    while (t--)
    {
        solve();
        newline
    }
}
 
ll GCD(ll numeroune, ll numerodeux)
{
    if (!numeroune)
    {
        return numerodeux;
    }
    return GCD(numerodeux % numeroune, numeroune);
}

ll LCM(ll numeroune, ll numerodeux)
{
    return numeroune * numerodeux / GCD(numeroune, numerodeux);
}

ll power(ll numeroune, ll numerodeux)
{
    ll res = 1;
    while (numerodeux) 
    {
        if (numerodeux & 1)
        { 
            res *= numeroune;
        }
        numeroune *= numeroune;
        numerodeux >>= 1;    
    }
    return res;
}

/*
$$$$$$$$\ $$$$$$$$\ 
$$  _____|\____$$  |
$$ |          $$  / 
$$$$$\       $$  /  
$$  __|     $$  /   
$$ |       $$  /    
$$$$$$$$\ $$$$$$$$\ 
\________|\________|
*/

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