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Submission #338604

# Submission time Handle Problem Language Result Execution time Memory
338604 2020-12-23T13:21:39 Z blue Mecho (IOI09_mecho) C++11
84 / 100
 1000 ms 8192 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;
    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;
    }

    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, 2e9) << '\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 487 ms 7916 KB Output is correct
8 Correct 0 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 Execution timed out 1077 ms 5604 KB Time limit exceeded
13 Incorrect 1 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 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 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 492 KB Output is correct
28 Correct 2 ms 492 KB Output is correct
29 Correct 1 ms 492 KB Output is correct
30 Correct 1 ms 492 KB Output is correct
31 Correct 2 ms 512 KB Output is correct
32 Correct 1 ms 492 KB Output is correct
33 Correct 12 ms 1772 KB Output is correct
34 Correct 11 ms 1872 KB Output is correct
35 Correct 176 ms 1872 KB Output is correct
36 Correct 11 ms 2284 KB Output is correct
37 Correct 12 ms 2432 KB Output is correct
38 Correct 229 ms 2412 KB Output is correct
39 Correct 15 ms 2796 KB Output is correct
40 Correct 18 ms 2796 KB Output is correct
41 Correct 287 ms 2924 KB Output is correct
42 Correct 16 ms 3308 KB Output is correct
43 Correct 32 ms 3308 KB Output is correct
44 Correct 359 ms 3436 KB Output is correct
45 Correct 20 ms 3948 KB Output is correct
46 Correct 24 ms 3948 KB Output is correct
47 Correct 446 ms 4076 KB Output is correct
48 Correct 26 ms 4588 KB Output is correct
49 Correct 36 ms 4588 KB Output is correct
50 Correct 532 ms 4764 KB Output is correct
51 Correct 32 ms 5356 KB Output is correct
52 Correct 35 ms 5356 KB Output is correct
53 Correct 674 ms 5504 KB Output is correct
54 Correct 40 ms 6124 KB Output is correct
55 Correct 43 ms 6124 KB Output is correct
56 Correct 729 ms 6300 KB Output is correct
57 Correct 36 ms 7020 KB Output is correct
58 Correct 56 ms 7020 KB Output is correct
59 Correct 843 ms 7144 KB Output is correct
60 Correct 41 ms 7936 KB Output is correct
61 Correct 50 ms 7916 KB Output is correct
62 Correct 987 ms 8044 KB Output is correct
63 Correct 298 ms 7916 KB Output is correct
64 Correct 759 ms 8020 KB Output is correct
65 Correct 580 ms 7916 KB Output is correct
66 Correct 391 ms 7924 KB Output is correct
67 Correct 332 ms 7924 KB Output is correct
68 Correct 184 ms 7916 KB Output is correct
69 Correct 130 ms 7916 KB Output is correct
70 Correct 89 ms 7916 KB Output is correct
71 Correct 93 ms 7836 KB Output is correct
72 Incorrect 65 ms 7916 KB Output isn't correct
73 Incorrect 151 ms 8044 KB Output isn't correct
74 Correct 372 ms 8108 KB Output is correct
75 Correct 288 ms 8048 KB Output is correct
76 Correct 270 ms 8172 KB Output is correct
77 Correct 314 ms 8024 KB Output is correct
78 Correct 383 ms 8040 KB Output is correct
79 Correct 318 ms 7916 KB Output is correct
80 Correct 294 ms 8092 KB Output is correct
81 Correct 309 ms 8044 KB Output is correct
82 Correct 281 ms 8044 KB Output is correct
83 Correct 384 ms 7916 KB Output is correct
84 Correct 430 ms 7916 KB Output is correct
85 Correct 328 ms 8044 KB Output is correct
86 Correct 373 ms 8044 KB Output is correct
87 Correct 373 ms 8172 KB Output is correct
88 Correct 423 ms 8192 KB Output is correct
89 Correct 549 ms 7916 KB Output is correct
90 Correct 460 ms 7916 KB Output is correct
91 Correct 480 ms 7992 KB Output is correct
92 Correct 546 ms 8056 KB Output is correct