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Submission #338600

# Submission time Handle Problem Language Result Execution time Memory
338600 2020-12-23T13:19:15 Z blue Mecho (IOI09_mecho) C++11
84 / 100
 1000 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;
vector<int> dist(800*800, 2e9);
//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;
    while(!tbv.empty())
    {
        u = tbv.front();
    //    cout << u << ' ' << dist[u] << '\n';
        tbv.pop();

        vector<int> edge; //check down
        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(dist[v] != INF) continue;
            if(dist[u] + 1 >= grid[v]) continue;
            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;
    }

    vector<int> visit(N*N, 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, 2e9) << '\n';
}

Subtask #1
84.0 / 100.0

# Verdict Execution time Memory Grader output
1 Correct 2 ms 2924 KB Output is correct
2 Correct 2 ms 2924 KB Output is correct
3 Correct 2 ms 2924 KB Output is correct
4 Correct 2 ms 2924 KB Output is correct
5 Correct 2 ms 2924 KB Output is correct
6 Correct 2 ms 2924 KB Output is correct
7 Correct 472 ms 7976 KB Output is correct
8 Correct 3 ms 2924 KB Output is correct
9 Correct 2 ms 2924 KB Output is correct
10 Correct 2 ms 2924 KB Output is correct
11 Correct 2 ms 2924 KB Output is correct
12 Execution timed out 1098 ms 7872 KB Time limit exceeded
13 Incorrect 3 ms 2924 KB Output isn't correct
14 Correct 3 ms 2924 KB Output is correct
15 Correct 2 ms 2924 KB Output is correct
16 Correct 2 ms 2924 KB Output is correct
17 Correct 2 ms 2924 KB Output is correct
18 Correct 2 ms 2924 KB Output is correct
19 Correct 2 ms 2924 KB Output is correct
20 Correct 2 ms 2924 KB Output is correct
21 Correct 2 ms 2924 KB Output is correct
22 Correct 3 ms 2924 KB Output is correct
23 Correct 2 ms 2924 KB Output is correct
24 Correct 3 ms 2924 KB Output is correct
25 Correct 2 ms 2924 KB Output is correct
26 Correct 2 ms 2924 KB Output is correct
27 Correct 2 ms 2924 KB Output is correct
28 Correct 2 ms 2924 KB Output is correct
29 Correct 2 ms 2924 KB Output is correct
30 Correct 3 ms 2924 KB Output is correct
31 Correct 3 ms 2924 KB Output is correct
32 Correct 3 ms 2924 KB Output is correct
33 Correct 13 ms 3820 KB Output is correct
34 Correct 13 ms 3820 KB Output is correct
35 Correct 167 ms 3948 KB Output is correct
36 Correct 16 ms 4076 KB Output is correct
37 Correct 13 ms 4076 KB Output is correct
38 Correct 224 ms 4076 KB Output is correct
39 Correct 18 ms 4588 KB Output is correct
40 Correct 22 ms 4460 KB Output is correct
41 Correct 301 ms 4588 KB Output is correct
42 Correct 18 ms 4972 KB Output is correct
43 Correct 31 ms 4844 KB Output is correct
44 Correct 350 ms 5012 KB Output is correct
45 Correct 24 ms 5228 KB Output is correct
46 Correct 35 ms 5228 KB Output is correct
47 Correct 495 ms 5228 KB Output is correct
48 Correct 30 ms 5740 KB Output is correct
49 Correct 37 ms 5740 KB Output is correct
50 Correct 567 ms 5872 KB Output is correct
51 Correct 38 ms 6124 KB Output is correct
52 Correct 33 ms 6124 KB Output is correct
53 Correct 610 ms 6124 KB Output is correct
54 Correct 44 ms 6764 KB Output is correct
55 Correct 44 ms 6764 KB Output is correct
56 Correct 803 ms 6892 KB Output is correct
57 Correct 39 ms 7276 KB Output is correct
58 Correct 55 ms 7276 KB Output is correct
59 Correct 820 ms 7456 KB Output is correct
60 Correct 46 ms 7916 KB Output is correct
61 Correct 43 ms 7916 KB Output is correct
62 Correct 1000 ms 8044 KB Output is correct
63 Correct 300 ms 7916 KB Output is correct
64 Correct 862 ms 8044 KB Output is correct
65 Correct 552 ms 7916 KB Output is correct
66 Correct 375 ms 7916 KB Output is correct
67 Correct 336 ms 7992 KB Output is correct
68 Correct 181 ms 7916 KB Output is correct
69 Correct 132 ms 8044 KB Output is correct
70 Correct 96 ms 7932 KB Output is correct
71 Correct 98 ms 7916 KB Output is correct
72 Incorrect 68 ms 7916 KB Output isn't correct
73 Incorrect 158 ms 8044 KB Output isn't correct
74 Correct 340 ms 8172 KB Output is correct
75 Correct 303 ms 8044 KB Output is correct
76 Correct 269 ms 8044 KB Output is correct
77 Correct 303 ms 8056 KB Output is correct
78 Correct 375 ms 8044 KB Output is correct
79 Correct 322 ms 8044 KB Output is correct
80 Correct 268 ms 8172 KB Output is correct
81 Correct 310 ms 8044 KB Output is correct
82 Correct 288 ms 8172 KB Output is correct
83 Correct 412 ms 7916 KB Output is correct
84 Correct 466 ms 8152 KB Output is correct
85 Correct 347 ms 8044 KB Output is correct
86 Correct 384 ms 8044 KB Output is correct
87 Correct 375 ms 8024 KB Output is correct
88 Correct 440 ms 8044 KB Output is correct
89 Correct 555 ms 8172 KB Output is correct
90 Correct 462 ms 8044 KB Output is correct
91 Correct 490 ms 7916 KB Output is correct
92 Correct 441 ms 8044 KB Output is correct