Submission #669098

#	Submission time	Handle	Problem	Language	Result	Execution time	Memory
669098	2022-12-05T16:24:07 Z	finn__	Mecho (IOI09_mecho)	C++17	100 / 100	353 ms	2560 KB

mecho

#include <bits/stdc++.h>
using namespace std;

struct point
{
    size_t i, j;
};

point M, D;
vector<point> H;

inline bool is_free(char x)
{
    return x == 'G' || x == 'M';
}

void spread_bees(vector<string> &forest, queue<point> &q)
{
    queue<point> y;

    while (!q.empty())
    {
        auto const [i, j] = q.front();
        q.pop();

        if (i && is_free(forest[i - 1][j]))
        {
            forest[i - 1][j] = 'B';
            y.push({i - 1, j});
        }

        if (i < forest.size() - 1 && is_free(forest[i + 1][j]))
        {
            forest[i + 1][j] = 'B';
            y.push({i + 1, j});
        }

        if (j && is_free(forest[i][j - 1]))
        {
            forest[i][j - 1] = 'B';
            y.push({i, j - 1});
        }

        if (j < forest.size() - 1 && is_free(forest[i][j + 1]))
        {
            forest[i][j + 1] = 'B';
            y.push({i, j + 1});
        }
    }

    swap(q, y);
}

bool walk_step(
    vector<string> const &forest, vector<vector<bool>> &vis, queue<point> &p)
{
    queue<point> y;

    while (!p.empty())
    {
        auto const [i, j] = p.front();
        p.pop();

        if (is_free(forest[i][j]))
        {
            if (i && !vis[i - 1][j])
            {
                if (is_free(forest[i - 1][j]))
                {
                    vis[i - 1][j] = 1;
                    y.push({i - 1, j});
                }
                else if (forest[i - 1][j] == 'D')
                    return 1;
            }

            if (i < forest.size() - 1 && !vis[i + 1][j])
            {
                if (is_free(forest[i + 1][j]))
                {
                    vis[i + 1][j] = 1;
                    y.push({i + 1, j});
                }
                else if (forest[i + 1][j] == 'D')
                    return 1;
            }

            if (j && !vis[i][j - 1])
            {
                if (is_free(forest[i][j - 1]))
                {
                    vis[i][j - 1] = 1;
                    y.push({i, j - 1});
                }
                else if (forest[i][j - 1] == 'D')
                    return 1;
            }

            if (j < forest.size() - 1 && !vis[i][j + 1])
            {
                if (is_free(forest[i][j + 1]))
                {
                    vis[i][j + 1] = 1;
                    y.push({i, j + 1});
                }
                else if (forest[i][j + 1] == 'D')
                    return 1;
            }
        }
    }

    swap(p, y);
    return 0;
}

bool can_go_home(size_t n, size_t s, vector<string> forest, unsigned t)
{
    queue<point> p, q;
    p.push(M);
    for (point const &x : H)
        q.push(x);

    vector<vector<bool>> vis(n, vector<bool>(n, 0));
    vis[M.i][M.j] = 1;

    for (unsigned i = 0; i < t; i++)
        spread_bees(forest, q);

    while (!p.empty())
    {
        for (size_t i = 0; i < s; i++)
        {
            if (walk_step(forest, vis, p))
                return 1;
        }
        spread_bees(forest, q);
    }

    return 0;
}

int main()
{
    size_t n, s;
    cin >> n >> s;

    vector<string> forest(n);
    for (size_t i = 0; i < n; i++)
    {
        cin >> forest[i];
        for (size_t j = 0; j < n; j++)
        {
            switch (forest[i][j])
            {
            case 'M':
                M = {i, j};
                break;
            case 'D':
                D = {i, j};
                break;
            case 'H':
                H.push_back({i, j});
                break;
            }
        }
    }

    unsigned a = 0, b = n * n;
    while (a < b)
    {
        unsigned t = (a + b + 1) / 2;

        if (can_go_home(n, s, forest, t))
            a = t;
        else
            b = t - 1;
    }

    if (!a && !can_go_home(n, s, forest, 0))
        cout << -1 << '\n';
    else
        cout << a << '\n';
}

Subtask #1

100.0 / 100.0

#	Verdict	Execution time	Memory	Grader output
1	Correct	0 ms	212 KB	Output is correct
2	Correct	0 ms	212 KB	Output is correct
3	Correct	0 ms	212 KB	Output is correct
4	Correct	0 ms	212 KB	Output is correct
5	Correct	0 ms	212 KB	Output is correct
6	Correct	0 ms	212 KB	Output is correct
7	Correct	224 ms	2120 KB	Output is correct
8	Correct	0 ms	212 KB	Output is correct
9	Correct	0 ms	212 KB	Output is correct
10	Correct	0 ms	212 KB	Output is correct
11	Correct	0 ms	212 KB	Output is correct
12	Correct	1 ms	212 KB	Output is correct
13	Correct	1 ms	212 KB	Output is correct
14	Correct	1 ms	212 KB	Output is correct
15	Correct	1 ms	212 KB	Output is correct
16	Correct	0 ms	212 KB	Output is correct
17	Correct	1 ms	212 KB	Output is correct
18	Correct	1 ms	212 KB	Output is correct
19	Correct	1 ms	212 KB	Output is correct
20	Correct	1 ms	212 KB	Output is correct
21	Correct	1 ms	212 KB	Output is correct
22	Correct	1 ms	212 KB	Output is correct
23	Correct	1 ms	212 KB	Output is correct
24	Correct	1 ms	212 KB	Output is correct
25	Correct	2 ms	212 KB	Output is correct
26	Correct	1 ms	212 KB	Output is correct
27	Correct	2 ms	212 KB	Output is correct
28	Correct	2 ms	212 KB	Output is correct
29	Correct	2 ms	212 KB	Output is correct
30	Correct	2 ms	212 KB	Output is correct
31	Correct	4 ms	212 KB	Output is correct
32	Correct	2 ms	212 KB	Output is correct
33	Correct	60 ms	596 KB	Output is correct
34	Correct	37 ms	596 KB	Output is correct
35	Correct	30 ms	596 KB	Output is correct
36	Correct	86 ms	712 KB	Output is correct
37	Correct	55 ms	596 KB	Output is correct
38	Correct	42 ms	724 KB	Output is correct
39	Correct	97 ms	796 KB	Output is correct
40	Correct	68 ms	852 KB	Output is correct
41	Correct	53 ms	792 KB	Output is correct
42	Correct	129 ms	1108 KB	Output is correct
43	Correct	84 ms	1108 KB	Output is correct
44	Correct	65 ms	1108 KB	Output is correct
45	Correct	165 ms	1220 KB	Output is correct
46	Correct	108 ms	1220 KB	Output is correct
47	Correct	77 ms	1216 KB	Output is correct
48	Correct	178 ms	1332 KB	Output is correct
49	Correct	123 ms	1336 KB	Output is correct
50	Correct	92 ms	1288 KB	Output is correct
51	Correct	222 ms	1468 KB	Output is correct
52	Correct	144 ms	1364 KB	Output is correct
53	Correct	110 ms	1472 KB	Output is correct
54	Correct	263 ms	1580 KB	Output is correct
55	Correct	170 ms	1576 KB	Output is correct
56	Correct	127 ms	1548 KB	Output is correct
57	Correct	303 ms	1712 KB	Output is correct
58	Correct	196 ms	1716 KB	Output is correct
59	Correct	150 ms	1620 KB	Output is correct
60	Correct	353 ms	1848 KB	Output is correct
61	Correct	229 ms	1852 KB	Output is correct
62	Correct	169 ms	1876 KB	Output is correct
63	Correct	221 ms	1996 KB	Output is correct
64	Correct	257 ms	1928 KB	Output is correct
65	Correct	213 ms	1876 KB	Output is correct
66	Correct	225 ms	1904 KB	Output is correct
67	Correct	224 ms	1876 KB	Output is correct
68	Correct	207 ms	1932 KB	Output is correct
69	Correct	182 ms	1936 KB	Output is correct
70	Correct	207 ms	1940 KB	Output is correct
71	Correct	201 ms	1876 KB	Output is correct
72	Correct	214 ms	1940 KB	Output is correct
73	Correct	193 ms	2548 KB	Output is correct
74	Correct	225 ms	2520 KB	Output is correct
75	Correct	243 ms	2524 KB	Output is correct
76	Correct	244 ms	2516 KB	Output is correct
77	Correct	241 ms	2560 KB	Output is correct
78	Correct	250 ms	2456 KB	Output is correct
79	Correct	237 ms	2388 KB	Output is correct
80	Correct	241 ms	2464 KB	Output is correct
81	Correct	239 ms	2444 KB	Output is correct
82	Correct	235 ms	2440 KB	Output is correct
83	Correct	254 ms	2388 KB	Output is correct
84	Correct	245 ms	2340 KB	Output is correct
85	Correct	249 ms	2336 KB	Output is correct
86	Correct	252 ms	2332 KB	Output is correct
87	Correct	236 ms	2464 KB	Output is correct
88	Correct	238 ms	2236 KB	Output is correct
89	Correct	240 ms	2132 KB	Output is correct
90	Correct	246 ms	2272 KB	Output is correct
91	Correct	226 ms	2284 KB	Output is correct
92	Correct	229 ms	2352 KB	Output is correct