Submission #1276163

#	Time	Username	Problem	Language	Result	Execution time	Memory
1276163		mnnit_prakharg	Mecho (IOI09_mecho)	C++20	40 / 100	254 ms	8788 KiB

mecho

#pragma GCC optimize("O3", "inline")
#include <bits/stdc++.h>
using namespace std;

typedef long long int ll;
typedef long double ld;
#define pb push_back
#define ub upper_bound

const ll INF = 1e18 + 100;

vector<int> ra = {-1, 0, 1, 0};
vector<int> ca = {0, 1, 0, -1};

int f(int n, vector<string> &a, int s, int m, vector<int> &sp, vector<int> &ep, vector<vector<ll>> &ftm)
{
    vector<vector<int>> v(n, vector<int>(n, 0));
    if (ftm[sp[0]][sp[1]] <= m)
        return 0;
    queue<vector<int>> q;
    q.push({sp[0], sp[1], m});
    v[sp[0]][sp[1]] = 1;
    while (!q.empty())
    {
        for (int i = 0; i < s; i++)
        {
            int sz = q.size();
            for (int j = 0; j < sz; j++)
            {
                auto del = q.front();
                q.pop();
                for (int d = 0; d < 4; d++)
                {
                    int nr = del[0] + ra[d], nc = del[1] + ca[d];
                    if (nr >= 0 && nr < n && nc >= 0 && nc < n && (a[nr][nc] == 'G' || a[nr][nc] == 'D') && ftm[nr][nc] > del[2] && !v[nr][nc])
                    {
                        if(nr == ep[0] && nc == ep[1]) return 1;
                        q.push({nr, nc, (i == s - 1 ? del[2] + 1 : del[2])});
                        v[nr][nc] = 1;
                    }
                }
            }
        }
    }
    return 0;
}

ll solve()
{
    int n, s;
    cin >> n >> s;
    vector<string> a(n);
    for (int i = 0; i < n; i++)
        cin >> a[i];
    vector<int> sp(2), ep(2);
    for (int i = 0; i < n; i++)
        for (int j = 0; j < n; j++)
        {
            if (a[i][j] == 'M')
                sp = {i, j};
            if (a[i][j] == 'D')
                ep = {i, j};
        }
    vector<vector<ll>> ftm(n, vector<ll>(n, INF));
    {
        queue<pair<int, int>> q;
        for (int i = 0; i < n; i++)
            for (int j = 0; j < n; j++)
            {
                if (a[i][j] == 'H')
                {
                    ftm[i][j] = 0;
                    q.push({i, j});
                }
            }
        while (!q.empty())
        {
            int sz = q.size();
            for (int i = 0; i < sz; i++)
            {
                auto del = q.front();
                q.pop();
                for (int d = 0; d < 4; d++)
                {
                    int nr = del.first + ra[d], nc = del.second + ca[d];
                    if (nr >= 0 && nr < n && nc >= 0 && nc < n && (a[nr][nc] == 'G' || a[nr][nc] == 'M') && ftm[nr][nc] == INF)
                    {
                        ftm[nr][nc] = ftm[del.first][del.second] + 1;
                        q.push({nr, nc});
                    }
                }
            }
        }
    }

    int l = 0, h = 2 * n, ma = -1;
    while (l <= h)
    {
        int m = (l + h) / 2;
        if (f(n, a, s, m, sp, ep, ftm))
        {
            ma = m;
            l = m + 1;
        }
        else
            h = m - 1;
    }
    return ma;
}

signed main()
{
    ios_base::sync_with_stdio(false);
    cin.tie(0);
    cout.tie(0);
    int t = 1;
    while (t--)
    {
        ll x = solve();
        cout << x << "\n";
    }
    return 0;
}

• Subtask 1: 40 / 100