답안 #338609

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
338609	2020-12-23T13:29:13 Z	blue	Mecho (IOI09_mecho)	C++11	84 / 100	253 ms	8172 KB

mecho

#include <iostream>
#include <vector>
#include <queue>
#include <set>
using namespace std;

/*
Mecho takes at most S steps per minute.
Bees spread every minute.

(*) Restatement:
Mecho takes at most 1 step every minute.
Bees spread at the end of every S'th minute.

For every location, compute the number of minutes before the location cannot be occupied anymore.
For trees and hives this number is zero.
Consider hives as -1
Consider
*/
int N, S;
int grid[800*800]; //the number of minutes before this location cannot be occupied anymore.
int mecho;
int home;
vector<int> edge;
int dist[800*800];
//LOOKS GOOD

int INF = 15e8;

int binary_search(int a, int b)
{
    // cout << "____________________________\n binary search " << a << ' ' << b << '\n';
    int m = (a+b)/2+1;
    if(a == b) m = a;

    //cout << mecho << ' ' << dist[mecho] << ' ' << home << '\n';
    for(int i = 0; i < N*N; i++) dist[i] = INF;

    queue<int> tbv;
    dist[mecho] = m;
    tbv.push(mecho);


    int u, v;
    while(!tbv.empty())
    {
        u = tbv.front();
    //    cout << u << ' ' << dist[u] << '\n';
        tbv.pop();

        vector<int> edge; //check down
        edge.clear();
        if(u % N != 0)
        {
            v = u-1;
            if(dist[v] == INF && dist[u] + 1 < grid[v])
            {
                dist[v] = dist[u] + 1;
                tbv.push(v);
            }
        }
        if(u % N != N-1)
        {
            v = u+1;
            if(dist[v] == INF && dist[u] + 1 < grid[v])
            {
                dist[v] = dist[u] + 1;
                tbv.push(v);
            }
        }
        if(u >= N)
        {
            v = u-N;
            if(dist[v] == INF && dist[u] + 1 < grid[v])
            {
                dist[v] = dist[u] + 1;
                tbv.push(v);
            }
        }
        if(u < N*(N+1))
        {
            v = u+N;
            if(dist[v] == INF && dist[u] + 1 < grid[v])
            {
                dist[v] = dist[u] + 1;
                tbv.push(v);
            }
        }

    }

    if(a == b)
    {
        if(dist[home] == INF) return -1;
        else return a/S;
    }
    else
    {
        if(dist[home] == INF) return binary_search(a, m-1);
        else return binary_search(m, b);
    }
}

int main()
{
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);

    char c;
    cin >> N >> S;

    for(int i = 0; i < N*N; i++)
    {
        cin >> c;
        if(c == 'T') grid[i] = 0;
        else if(c == 'G') grid[i] = INF;
        else if(c == 'M')
        {
            grid[i] = INF;
            mecho = i;
        }
        else if(c == 'D')
        {
            grid[i] = 0;
            home = i;
        }
        else grid[i] = -1;
    }

    int visit[N*N];
    for(int i = 0; i < N*N; i++) visit[i] = 0;

    queue<int> tbv;

    for(int i = 0; i < N*N; i++)
    {
        if(grid[i] != -1) continue;
        grid[i] = 0;
        tbv.push(i);
        visit[i] = 1;
    }

    while(tbv.size() > 0)
    {
        int u = tbv.front();
        tbv.pop();

        edge.clear();
        if(u % N > 0) edge.push_back(u-1);
        if(u % N < N-1) edge.push_back(u+1);
        if(u >= N) edge.push_back(u-N);
        if(u < N*(N-1)) edge.push_back(u+N);

        for(int v: edge)
        {
            if(visit[v]) continue;
            if(grid[v] > grid[u] + S)
            {
                grid[v] = grid[u] + S;
                tbv.push(v);
            }
        }
    }

    grid[home] = INF;

    // for(int i = 0; i < N*N; i++)
    // {
    //     cout << grid[i] << ' ';
    //     if(i % N == N-1) cout << '\n';
    // }

    cout << binary_search(0, 2e8) << '\n';
}

Subtask #1

84.0 / 100.0

#	결과	실행 시간	메모리	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	364 KB	Output is correct
7	Correct	99 ms	7916 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	1 ms	364 KB	Output isn't correct
13	Incorrect	1 ms	364 KB	Output isn't correct
14	Correct	1 ms	364 KB	Output is correct
15	Correct	1 ms	492 KB	Output is correct
16	Correct	1 ms	364 KB	Output is correct
17	Correct	1 ms	364 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	384 KB	Output is correct
22	Correct	1 ms	364 KB	Output is correct
23	Correct	1 ms	364 KB	Output is correct
24	Correct	1 ms	364 KB	Output is correct
25	Correct	1 ms	364 KB	Output is correct
26	Correct	1 ms	364 KB	Output is correct
27	Correct	1 ms	364 KB	Output is correct
28	Correct	1 ms	384 KB	Output is correct
29	Correct	1 ms	364 KB	Output is correct
30	Correct	1 ms	364 KB	Output is correct
31	Correct	1 ms	364 KB	Output is correct
32	Correct	1 ms	492 KB	Output is correct
33	Correct	7 ms	1772 KB	Output is correct
34	Correct	8 ms	1772 KB	Output is correct
35	Correct	23 ms	1772 KB	Output is correct
36	Correct	9 ms	2284 KB	Output is correct
37	Correct	11 ms	2284 KB	Output is correct
38	Correct	35 ms	2284 KB	Output is correct
39	Correct	11 ms	2796 KB	Output is correct
40	Correct	12 ms	2796 KB	Output is correct
41	Correct	42 ms	2796 KB	Output is correct
42	Correct	14 ms	3308 KB	Output is correct
43	Correct	14 ms	3308 KB	Output is correct
44	Correct	50 ms	3308 KB	Output is correct
45	Correct	16 ms	3948 KB	Output is correct
46	Correct	17 ms	3948 KB	Output is correct
47	Correct	61 ms	3948 KB	Output is correct
48	Correct	20 ms	4716 KB	Output is correct
49	Correct	19 ms	4588 KB	Output is correct
50	Correct	107 ms	4588 KB	Output is correct
51	Correct	23 ms	5356 KB	Output is correct
52	Correct	24 ms	5356 KB	Output is correct
53	Correct	100 ms	5484 KB	Output is correct
54	Correct	26 ms	6124 KB	Output is correct
55	Correct	30 ms	6124 KB	Output is correct
56	Correct	116 ms	6124 KB	Output is correct
57	Correct	31 ms	7020 KB	Output is correct
58	Correct	38 ms	7020 KB	Output is correct
59	Correct	144 ms	7020 KB	Output is correct
60	Correct	35 ms	7916 KB	Output is correct
61	Correct	35 ms	7916 KB	Output is correct
62	Correct	182 ms	7916 KB	Output is correct
63	Correct	115 ms	7916 KB	Output is correct
64	Correct	253 ms	8044 KB	Output is correct
65	Correct	155 ms	7916 KB	Output is correct
66	Correct	139 ms	7916 KB	Output is correct
67	Correct	125 ms	8044 KB	Output is correct
68	Correct	84 ms	7804 KB	Output is correct
69	Correct	88 ms	7916 KB	Output is correct
70	Correct	64 ms	7900 KB	Output is correct
71	Correct	65 ms	7916 KB	Output is correct
72	Incorrect	54 ms	7916 KB	Output isn't correct
73	Incorrect	59 ms	8044 KB	Output isn't correct
74	Correct	75 ms	8044 KB	Output is correct
75	Correct	74 ms	8044 KB	Output is correct
76	Correct	71 ms	8172 KB	Output is correct
77	Correct	77 ms	8044 KB	Output is correct
78	Correct	90 ms	8044 KB	Output is correct
79	Correct	78 ms	7916 KB	Output is correct
80	Correct	88 ms	7916 KB	Output is correct
81	Correct	71 ms	7916 KB	Output is correct
82	Correct	72 ms	8044 KB	Output is correct
83	Correct	85 ms	7916 KB	Output is correct
84	Correct	88 ms	7916 KB	Output is correct
85	Correct	79 ms	7916 KB	Output is correct
86	Correct	90 ms	7916 KB	Output is correct
87	Correct	103 ms	7916 KB	Output is correct
88	Correct	118 ms	7916 KB	Output is correct
89	Correct	108 ms	7916 KB	Output is correct
90	Correct	109 ms	7916 KB	Output is correct
91	Correct	101 ms	8044 KB	Output is correct
92	Correct	93 ms	7916 KB	Output is correct