Submission #386521

#	Submission time	Handle	Problem	Language	Result	Execution time	Memory
386521	2021-04-06T17:50:34 Z	SansPapyrus683	Mecho (IOI09_mecho)	C++17	84 / 100	685 ms	7756 KB

mecho

#include <iostream>
#include <vector>
#include <queue>
#include <climits>

using std::cout;
using std::endl;
using std::vector;
using std::pair;

vector<pair<int, int>> neighbors(const pair<int, int>& at, int row_num, int col_num) {
    vector<pair<int, int>> neighbors;
    if (at.first > 0) {
        neighbors.push_back({at.first - 1, at.second});
    }
    if (at.second > 0) {
        neighbors.push_back({at.first, at.second - 1});
    }
    if (at.first < row_num - 1) {
        neighbors.push_back({at.first + 1, at.second});
    }
    if (at.second < col_num - 1) {
        neighbors.push_back({at.first, at.second + 1});
    }
    return neighbors;
}

class Field {
    private:
        const vector<vector<char>> field;
        const int row_num;
        const int col_num;
        pair<int, int> start;
        vector<vector<int>> bee_dists;
    public:
        Field(const vector<vector<char>>& field)
                : field(field), row_num(field.size()), col_num(field[0].size()),
                  bee_dists(row_num, vector<int>(col_num, INT_MAX)) {
            std::queue<pair<int, int>> frontier;
            for (int r = 0; r < row_num; r++) {
                for (int c = 0; c < col_num; c++) {
                    if (field[r][c] == 'H') {
                        frontier.push({r, c});
                        bee_dists[r][c] = 0;
                    } else if (field[r][c] == 'M') {
                        start = {r, c};
                    }
                }
            }
            while (!frontier.empty()) {
                pair<int, int> c = frontier.front();  // c for curr and to reduce my line length
                frontier.pop();
                int n_cost = bee_dists[c.first][c.second] + 1;
                for (const pair<int, int>& n : neighbors(c, row_num, col_num)) {
                    if (n_cost < bee_dists[n.first][n.second]
                            && field[n.first][n.second] != 'T'
                            && field[n.first][n.second] != 'D') {
                        bee_dists[n.first][n.second] = n_cost;
                        frontier.push(n);
                    }
                }
            }
        }

        bool can_go_home(int honey_time, int speed) {
            std::queue<pair<int, int>> frontier;
            vector<vector<int>> min_moves(row_num, vector<int>(col_num, INT_MAX));
            frontier.push(start);
            min_moves[start.first][start.second] = honey_time * speed;
            while (!frontier.empty()) {
                pair<int, int> curr = frontier.front();
                frontier.pop();
                if (field[curr.first][curr.second] == 'D') {
                    return true;
                }
                int n_cost = min_moves[curr.first][curr.second] + 1;
                for (const pair<int, int>& n : neighbors(curr, row_num, col_num)) {
                    if (field[n.first][n.second] != 'T'
                            && (n_cost / speed) < bee_dists[n.first][n.second]
                            && n_cost < min_moves[n.first][n.second]) {
                        min_moves[n.first][n.second] = n_cost;
                        frontier.push(n);
                    }
                }
            }
            return false;
        }
};

// https://oj.uz/problem/view/IOI09_mecho (sample input ommitted)
int main() {
    int side_len;
    int speed;
    std::cin >> side_len >> speed;
    vector<vector<char>> grid(side_len, vector<char>(side_len));
    for (int r = 0; r < side_len; r++) {
        for (int c = 0; c < side_len; c++) {
            std::cin >> grid[r][c];
        }
    }

    Field field(grid);
    int lo = 0;
    int hi = side_len * side_len;
    int valid = -1;
    while (lo <= hi) {
        int mid = (lo + hi) / 2;
        if (field.can_go_home(mid, speed)) {
            valid = mid;
            lo = mid + 1;
        } else {
            hi = mid - 1;
        }
    }
    cout << valid << endl;
}

Subtask #1

84.0 / 100.0

#	Verdict	Execution time	Memory	Grader output
1	Correct	1 ms	364 KB	Output is correct
2	Correct	1 ms	364 KB	Output is correct
3	Correct	1 ms	364 KB	Output is correct
4	Correct	1 ms	364 KB	Output is correct
5	Correct	1 ms	364 KB	Output is correct
6	Correct	1 ms	384 KB	Output is correct
7	Correct	442 ms	7500 KB	Output is correct
8	Correct	1 ms	364 KB	Output is correct
9	Correct	1 ms	364 KB	Output is correct
10	Correct	1 ms	364 KB	Output is correct
11	Correct	1 ms	364 KB	Output is correct
12	Incorrect	2 ms	364 KB	Output isn't correct
13	Incorrect	2 ms	364 KB	Output isn't correct
14	Correct	2 ms	364 KB	Output is correct
15	Correct	1 ms	364 KB	Output is correct
16	Correct	1 ms	364 KB	Output is correct
17	Correct	1 ms	384 KB	Output is correct
18	Correct	1 ms	364 KB	Output is correct
19	Correct	1 ms	364 KB	Output is correct
20	Correct	1 ms	364 KB	Output is correct
21	Correct	1 ms	364 KB	Output is correct
22	Correct	1 ms	364 KB	Output is correct
23	Correct	1 ms	364 KB	Output is correct
24	Correct	2 ms	364 KB	Output is correct
25	Correct	2 ms	364 KB	Output is correct
26	Correct	2 ms	364 KB	Output is correct
27	Correct	2 ms	384 KB	Output is correct
28	Correct	2 ms	364 KB	Output is correct
29	Correct	2 ms	364 KB	Output is correct
30	Correct	2 ms	384 KB	Output is correct
31	Correct	2 ms	364 KB	Output is correct
32	Correct	2 ms	364 KB	Output is correct
33	Correct	22 ms	1612 KB	Output is correct
34	Correct	20 ms	1724 KB	Output is correct
35	Correct	96 ms	1796 KB	Output is correct
36	Correct	24 ms	1996 KB	Output is correct
37	Correct	29 ms	2156 KB	Output is correct
38	Correct	146 ms	2476 KB	Output is correct
39	Correct	31 ms	2412 KB	Output is correct
40	Correct	32 ms	2612 KB	Output is correct
41	Correct	171 ms	2728 KB	Output is correct
42	Correct	41 ms	2940 KB	Output is correct
43	Correct	42 ms	3200 KB	Output is correct
44	Correct	215 ms	3164 KB	Output is correct
45	Correct	47 ms	3532 KB	Output is correct
46	Correct	50 ms	3740 KB	Output is correct
47	Correct	243 ms	3724 KB	Output is correct
48	Correct	52 ms	3996 KB	Output is correct
49	Correct	65 ms	4372 KB	Output is correct
50	Correct	305 ms	4324 KB	Output is correct
51	Correct	64 ms	4664 KB	Output is correct
52	Correct	70 ms	5072 KB	Output is correct
53	Correct	376 ms	5240 KB	Output is correct
54	Correct	74 ms	5332 KB	Output is correct
55	Correct	77 ms	5820 KB	Output is correct
56	Correct	444 ms	6004 KB	Output is correct
57	Correct	84 ms	6044 KB	Output is correct
58	Correct	91 ms	6808 KB	Output is correct
59	Correct	535 ms	6628 KB	Output is correct
60	Correct	97 ms	6912 KB	Output is correct
61	Correct	101 ms	7524 KB	Output is correct
62	Correct	592 ms	7592 KB	Output is correct
63	Correct	358 ms	7472 KB	Output is correct
64	Correct	685 ms	7572 KB	Output is correct
65	Correct	517 ms	7620 KB	Output is correct
66	Correct	414 ms	7444 KB	Output is correct
67	Correct	390 ms	7444 KB	Output is correct
68	Correct	181 ms	7596 KB	Output is correct
69	Correct	178 ms	7508 KB	Output is correct
70	Correct	142 ms	7488 KB	Output is correct
71	Correct	164 ms	7700 KB	Output is correct
72	Incorrect	129 ms	7532 KB	Output isn't correct
73	Incorrect	202 ms	7568 KB	Output isn't correct
74	Correct	279 ms	7756 KB	Output is correct
75	Correct	340 ms	7456 KB	Output is correct
76	Correct	302 ms	7568 KB	Output is correct
77	Correct	318 ms	7480 KB	Output is correct
78	Correct	366 ms	7448 KB	Output is correct
79	Correct	267 ms	7488 KB	Output is correct
80	Correct	293 ms	7480 KB	Output is correct
81	Correct	327 ms	7480 KB	Output is correct
82	Correct	305 ms	7484 KB	Output is correct
83	Correct	392 ms	7444 KB	Output is correct
84	Correct	360 ms	7468 KB	Output is correct
85	Correct	378 ms	7476 KB	Output is correct
86	Correct	377 ms	7468 KB	Output is correct
87	Correct	378 ms	7464 KB	Output is correct
88	Correct	392 ms	7600 KB	Output is correct
89	Correct	413 ms	7468 KB	Output is correct
90	Correct	423 ms	7456 KB	Output is correct
91	Correct	409 ms	7584 KB	Output is correct
92	Correct	444 ms	7496 KB	Output is correct