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Submission #338608

# Submission time Handle Problem Language Result Execution time Memory
338608 2020-12-23T13:26:33 Z blue Mecho (IOI09_mecho) C++11
84 / 100
 243 ms 8172 KB 
#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 = 2e9;

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

# 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 364 KB Output is correct
7 Correct 109 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 364 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 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 1 ms 512 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 512 KB Output is correct
29 Correct 1 ms 364 KB Output is correct
30 Correct 1 ms 376 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 10 ms 1772 KB Output is correct
35 Correct 22 ms 1772 KB Output is correct
36 Correct 9 ms 2284 KB Output is correct
37 Correct 9 ms 2284 KB Output is correct
38 Correct 31 ms 2284 KB Output is correct
39 Correct 11 ms 2796 KB Output is correct
40 Correct 13 ms 2796 KB Output is correct
41 Correct 43 ms 2944 KB Output is correct
42 Correct 14 ms 3308 KB Output is correct
43 Correct 15 ms 3308 KB Output is correct
44 Correct 48 ms 3308 KB Output is correct
45 Correct 18 ms 3948 KB Output is correct
46 Correct 22 ms 3948 KB Output is correct
47 Correct 77 ms 3948 KB Output is correct
48 Correct 20 ms 4588 KB Output is correct
49 Correct 24 ms 4588 KB Output is correct
50 Correct 79 ms 4540 KB Output is correct
51 Correct 26 ms 5356 KB Output is correct
52 Correct 24 ms 5356 KB Output is correct
53 Correct 114 ms 5484 KB Output is correct
54 Correct 30 ms 6124 KB Output is correct
55 Correct 28 ms 6124 KB Output is correct
56 Correct 133 ms 6380 KB Output is correct
57 Correct 31 ms 7020 KB Output is correct
58 Correct 38 ms 7020 KB Output is correct
59 Correct 155 ms 7148 KB Output is correct
60 Correct 34 ms 7916 KB Output is correct
61 Correct 37 ms 7916 KB Output is correct
62 Correct 177 ms 7924 KB Output is correct
63 Correct 113 ms 7916 KB Output is correct
64 Correct 243 ms 8044 KB Output is correct
65 Correct 160 ms 7916 KB Output is correct
66 Correct 158 ms 7916 KB Output is correct
67 Correct 126 ms 7916 KB Output is correct
68 Correct 82 ms 7916 KB Output is correct
69 Correct 75 ms 7916 KB Output is correct
70 Correct 66 ms 7916 KB Output is correct
71 Correct 62 ms 7916 KB Output is correct
72 Incorrect 52 ms 7916 KB Output isn't correct
73 Incorrect 62 ms 8044 KB Output isn't correct
74 Correct 95 ms 8052 KB Output is correct
75 Correct 76 ms 8044 KB Output is correct
76 Correct 72 ms 8172 KB Output is correct
77 Correct 82 ms 8044 KB Output is correct
78 Correct 86 ms 7916 KB Output is correct
79 Correct 79 ms 7916 KB Output is correct
80 Correct 72 ms 7916 KB Output is correct
81 Correct 72 ms 7916 KB Output is correct
82 Correct 74 ms 8044 KB Output is correct
83 Correct 92 ms 8016 KB Output is correct
84 Correct 99 ms 7916 KB Output is correct
85 Correct 83 ms 8044 KB Output is correct
86 Correct 87 ms 7916 KB Output is correct
87 Correct 88 ms 7916 KB Output is correct
88 Correct 98 ms 7916 KB Output is correct
89 Correct 103 ms 7916 KB Output is correct
90 Correct 94 ms 7916 KB Output is correct
91 Correct 102 ms 7916 KB Output is correct
92 Correct 98 ms 7916 KB Output is correct