Submission #632619

#	Time	Username	Problem	Language	Result	Execution time	Memory
632619		VasLemmy	Tracks in the Snow (BOI13_tracks)	C++17	100 / 100	600 ms	169152 KiB

tracks

#include<bits/stdc++.h>
//#define int long long
#define pii pair<int,ll>
#define fi first
#define se second
/*#pragma GCC target ("avx2")
#pragma GCC optimization ("O3")
#pragma GCC optimization ("unroll-loops")
#pragma GCC optimize("Ofast")
#pragma GCC target("avx,avx2,fma")*/
using namespace std;
using ll = long long;
using ull = unsigned long long;
using ldb = long double;
const ll N = (int)1e6;
const int maxN = (int)3e5 + 5;
const int mod = 1e9 + 7;
//const int mod = 998244353;
const ll infty = 1e18 + 7;
const int base = (int)4e5;
const int Block_size = 350;

void InputFile()
{
    //freopen("threesum.in","r",stdin);
    //freopen("threesum.out","w",stdout);
    //freopen("test.out","r",stdin);
}

void FastInput()
{
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);
}

int n,m;
char a[4005][4005];
int dp[4005][4005];

void Read()
{
    cin >> m >> n;
    for(int i = 1; i <= m; i++)
    {
        for(int j = 1; j <= n; j++)
        {
            cin >> a[i][j];
            //dp[i][j] = mod;
        }
    }

    deque<pii>  q;
    dp[1][1] = 1;
    q.push_back({1,1});
    int res = 0;
    do
    {
        pii u = q.front();
        res = max(res,dp[u.fi][u.se]);
        q.pop_front();
        pii v = {u.fi,u.se+1};
        if(v.se <= n && a[v.fi][v.se] != '.')
        {
            if(!dp[v.fi][v.se])
            {
                dp[v.fi][v.se] = dp[u.fi][u.se] + (a[u.fi][u.se] != a[v.fi][v.se]);
                if(a[u.fi][u.se] != a[v.fi][v.se]) q.push_back(v);
                else q.push_front(v);
            }
        }

        v = {u.fi+1,u.se};
        if(v.fi <= m && a[v.fi][v.se] != '.')
        {
            if(!dp[v.fi][v.se])
            {
                dp[v.fi][v.se] = dp[u.fi][u.se] + (a[u.fi][u.se] != a[v.fi][v.se]);
                if(a[u.fi][u.se] != a[v.fi][v.se]) q.push_back(v);
                else q.push_front(v);
            }
        }

        v = {u.fi-1,u.se};
        if(v.fi >= 1 && a[v.fi][v.se] != '.')
        {
            if(!dp[v.fi][v.se])
            {
                dp[v.fi][v.se] = dp[u.fi][u.se] + (a[u.fi][u.se] != a[v.fi][v.se]);
                if(a[u.fi][u.se] != a[v.fi][v.se]) q.push_back(v);
                else q.push_front(v);
            }
        }

        v = {u.fi,u.se-1};
        if(v.se >= 1 && a[v.fi][v.se] != '.')
        {
            if(!dp[v.fi][v.se])
            {
                dp[v.fi][v.se] = dp[u.fi][u.se] + (a[u.fi][u.se] != a[v.fi][v.se]);
                if(a[u.fi][u.se] != a[v.fi][v.se]) q.push_back(v);
                else q.push_front(v);
            }
        }
    }
    while(!q.empty());

    cout << res;
    /*for(int i = 1;i <= m;i++)
    {
        for(int j = 1;j <= n;j++)
        {
            cout << dp[i][j] <<' ';
        }
        cout <<'\n';
    }*/
}

void Solve()
{

}

void Debug()
{

}


int32_t main()
{
    FastInput();
    //InputFile();
    //int sub_type;
    //cin >> sub_type;
    //Sieve()
    int test;
    //cin >> test;
    test = 1;
    while(test--)
    {
        Read();
        Solve();
        //Debug();
    }
}
////
/////
//////

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