oj.uz

Submission #547635

# Submission time Handle Problem Language Result Execution time Memory
547635 2022-04-11T06:36:52 Z pancankes Mecho (IOI09_mecho) C++17
95 / 100
 233 ms 11704 KB 
#include <iostream>
#include <vector>
#include <algorithm>
#include <set>
#include <map>
#include <queue>
#include <cmath>
using namespace std;
#define int long long
const int INF=1e18;
const int MAXN=801;

int n,s,ans=0;
string grid[MAXN];
int bee[MAXN][MAXN],dist[MAXN][MAXN];
vector<pair<int,int>> hives;
pair<int,int> start,dest;

int dx[4]{1, -1, 0, 0}, dy[4]{0, 0, 1, -1};
bool inside(int x, int y) {
	return (x > -1 && x < n && y > -1 && y < n && grid[x][y] != 'T' && grid[x][y]!='D');
}

void setIO(string name="") { 
    ios_base::sync_with_stdio(0); cin.tie(0); 
    if (!name.empty()) {
        freopen((name+".in").c_str(), "r", stdin); 
        freopen((name+".out").c_str(), "w", stdout);
    }
}

// check if after eating for t seconds,
// is it possible to reach the destination
bool check(int t)
{
    for (int i=0; i<n; i++)
        for (int j=0; j<n; j++)
            dist[i][j]=INF;
    queue<pair<int,int>>q;
    if (bee[start.first][start.second]>t) q.push(start);
    dist[start.first][start.second]=0;
    while (!q.empty())
    {
        pair<int,int> c=q.front();
        q.pop();

        for (int i=0; i<4; i++)
        {
            int x=c.first+dx[i],y=c.second+dy[i];
            // if i can usually get there in 7 step
            // taking 2 steps a minute i can get there in ceil(7/2) steps
            if (inside(x,y)&&dist[x][y]==INF&&(bee[x][y]-t)>(dist[c.first][c.second]+1)/s)
            {
                dist[x][y]=dist[c.first][c.second]+1;
                q.push({x,y});
            }
        }
    }
    // cout << t << endl;
    // for (int i=0; i<n; i++) {for (int j=0; j<n; j++) cout << dist[i][j] << " "; cout << endl;}
    bool reached=false;
    for (int i=0; i<4; i++)
    {
        int x=dest.first+dx[i],y=dest.second+dy[i];
        if (inside(x,y)&&dist[x][y]!=INF)
            reached=true;
    }
    return reached;
}

int32_t main()
{
    cin >> n >> s;
    for (int i=0; i<n; i++) cin >> grid[i];
    for (int i=0; i<n; i++)
        for (int j=0; j<n; j++)
        {
            if (grid[i][j]=='M') start={i,j};
            if (grid[i][j]=='D') dest={i,j};
            if (grid[i][j]=='H') hives.push_back({i,j});
            bee[i][j]=INF;
        }
    // multisource bfs to find the distances of cells from hive
    queue<pair<int,int>> q;
    for (int i=0; i<hives.size(); i++) {
        q.push(hives[i]);
        bee[hives[i].first][hives[i].second]=0;
    }
    while (!q.empty())
    {
        pair<int,int> c=q.front();
        q.pop();
        for (int i=0; i<4; i++)
        {
            int x=c.first+dx[i],y=c.second+dy[i];
            if (inside(x,y)&&grid[x][y]!='D'&&bee[x][y]==INF)
            {
                bee[x][y]=bee[c.first][c.second]+1;
                q.push({x,y});
            }
        }
    }
    // for (int i=0; i<n; i++) {for (int j=0; j<n; j++) cout << bee[i][j] << " "; cout << endl;} cout << endl;
    int lo=0,hi=n*n;
    while (lo<=hi)
    {
        int mid=lo+(hi-lo)/2;
        // cout << mid << endl;
        if (check(mid))
        {
            ans=max(ans,mid);
            lo=mid+1;
        }
        else hi=mid-1;
    }
    if (!check(0)) cout << -1 << endl;
    else cout << ans << endl;
}

Compilation message

mecho.cpp: In function 'int32_t main()':
mecho.cpp:85:20: warning: comparison of integer expressions of different signedness: 'long long int' and 'std::vector<std::pair<long long int, long long int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   85 |     for (int i=0; i<hives.size(); i++) {
      |                   ~^~~~~~~~~~~~~
mecho.cpp: In function 'void setIO(std::string)':
mecho.cpp:27:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   27 |         freopen((name+".in").c_str(), "r", stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
mecho.cpp:28:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   28 |         freopen((name+".out").c_str(), "w", stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Subtask #1
95.0 / 100.0

# Verdict Execution time Memory Grader output
1 Correct 1 ms 340 KB Output is correct
2 Correct 1 ms 340 KB Output is correct
3 Correct 0 ms 340 KB Output is correct
4 Correct 0 ms 340 KB Output is correct
5 Correct 0 ms 340 KB Output is correct
6 Correct 0 ms 340 KB Output is correct
7 Correct 96 ms 11276 KB Output is correct
8 Correct 0 ms 340 KB Output is correct
9 Correct 0 ms 340 KB Output is correct
10 Correct 0 ms 340 KB Output is correct
11 Correct 0 ms 340 KB Output is correct
12 Incorrect 1 ms 852 KB Output isn't correct
13 Correct 1 ms 724 KB Output is correct
14 Correct 1 ms 852 KB Output is correct
15 Correct 1 ms 468 KB Output is correct
16 Correct 1 ms 468 KB Output is correct
17 Correct 1 ms 468 KB Output is correct
18 Correct 1 ms 468 KB Output is correct
19 Correct 1 ms 596 KB Output is correct
20 Correct 1 ms 596 KB Output is correct
21 Correct 1 ms 596 KB Output is correct
22 Correct 1 ms 596 KB Output is correct
23 Correct 1 ms 724 KB Output is correct
24 Correct 1 ms 708 KB Output is correct
25 Correct 1 ms 852 KB Output is correct
26 Correct 1 ms 852 KB Output is correct
27 Correct 1 ms 852 KB Output is correct
28 Correct 1 ms 852 KB Output is correct
29 Correct 1 ms 980 KB Output is correct
30 Correct 1 ms 980 KB Output is correct
31 Correct 1 ms 980 KB Output is correct
32 Correct 1 ms 980 KB Output is correct
33 Correct 8 ms 4892 KB Output is correct
34 Correct 9 ms 4820 KB Output is correct
35 Correct 26 ms 4820 KB Output is correct
36 Correct 11 ms 5460 KB Output is correct
37 Correct 12 ms 5496 KB Output is correct
38 Correct 30 ms 5460 KB Output is correct
39 Correct 13 ms 6192 KB Output is correct
40 Correct 17 ms 6100 KB Output is correct
41 Correct 42 ms 6228 KB Output is correct
42 Correct 18 ms 7012 KB Output is correct
43 Correct 17 ms 7076 KB Output is correct
44 Correct 50 ms 7076 KB Output is correct
45 Correct 19 ms 7768 KB Output is correct
46 Correct 21 ms 7636 KB Output is correct
47 Correct 56 ms 7764 KB Output is correct
48 Correct 20 ms 8412 KB Output is correct
49 Correct 22 ms 8404 KB Output is correct
50 Correct 76 ms 8404 KB Output is correct
51 Correct 25 ms 9040 KB Output is correct
52 Correct 28 ms 9000 KB Output is correct
53 Correct 89 ms 9044 KB Output is correct
54 Correct 34 ms 9660 KB Output is correct
55 Correct 32 ms 9684 KB Output is correct
56 Correct 104 ms 9780 KB Output is correct
57 Correct 35 ms 10496 KB Output is correct
58 Correct 34 ms 10360 KB Output is correct
59 Correct 124 ms 10464 KB Output is correct
60 Correct 38 ms 11092 KB Output is correct
61 Correct 40 ms 11088 KB Output is correct
62 Correct 154 ms 11124 KB Output is correct
63 Correct 129 ms 11124 KB Output is correct
64 Correct 233 ms 11120 KB Output is correct
65 Correct 175 ms 11108 KB Output is correct
66 Correct 151 ms 11120 KB Output is correct
67 Correct 145 ms 11248 KB Output is correct
68 Correct 67 ms 11140 KB Output is correct
69 Correct 71 ms 11172 KB Output is correct
70 Correct 53 ms 11184 KB Output is correct
71 Correct 68 ms 11180 KB Output is correct
72 Correct 50 ms 11184 KB Output is correct
73 Correct 48 ms 11704 KB Output is correct
74 Correct 84 ms 11688 KB Output is correct
75 Correct 81 ms 11640 KB Output is correct
76 Correct 71 ms 11600 KB Output is correct
77 Correct 75 ms 11664 KB Output is correct
78 Correct 85 ms 11652 KB Output is correct
79 Correct 73 ms 11600 KB Output is correct
80 Correct 74 ms 11644 KB Output is correct
81 Correct 78 ms 11644 KB Output is correct
82 Correct 72 ms 11540 KB Output is correct
83 Correct 93 ms 11564 KB Output is correct
84 Correct 94 ms 11556 KB Output is correct
85 Correct 93 ms 11552 KB Output is correct
86 Correct 93 ms 11472 KB Output is correct
87 Correct 86 ms 11468 KB Output is correct
88 Correct 93 ms 11456 KB Output is correct
89 Correct 105 ms 11440 KB Output is correct
90 Correct 102 ms 11452 KB Output is correct
91 Correct 102 ms 11376 KB Output is correct
92 Correct 101 ms 11392 KB Output is correct