oj.uz

Submission #547625

# Submission time Handle Problem Language Result Execution time Memory
547625 2022-04-11T06:17:19 Z pancankes Mecho (IOI09_mecho) C++17
84 / 100
 230 ms 11716 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
84.0 / 100.0

# Verdict Execution time Memory Grader output
1 Correct 0 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 1 ms 340 KB Output is correct
5 Correct 0 ms 340 KB Output is correct
6 Correct 1 ms 340 KB Output is correct
7 Correct 97 ms 11328 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 Incorrect 1 ms 724 KB Output isn't correct
14 Correct 1 ms 852 KB Output is correct
15 Correct 0 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 0 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 724 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 4820 KB Output is correct
34 Correct 9 ms 4820 KB Output is correct
35 Correct 23 ms 4852 KB Output is correct
36 Correct 11 ms 5444 KB Output is correct
37 Correct 11 ms 5460 KB Output is correct
38 Correct 29 ms 5460 KB Output is correct
39 Correct 14 ms 6200 KB Output is correct
40 Correct 14 ms 6100 KB Output is correct
41 Correct 45 ms 6100 KB Output is correct
42 Correct 15 ms 7084 KB Output is correct
43 Correct 17 ms 6996 KB Output is correct
44 Correct 50 ms 7020 KB Output is correct
45 Correct 20 ms 7760 KB Output is correct
46 Correct 21 ms 7656 KB Output is correct
47 Correct 58 ms 7764 KB Output is correct
48 Correct 22 ms 8404 KB Output is correct
49 Correct 22 ms 8364 KB Output is correct
50 Correct 70 ms 8420 KB Output is correct
51 Correct 27 ms 8996 KB Output is correct
52 Correct 26 ms 9044 KB Output is correct
53 Correct 87 ms 9100 KB Output is correct
54 Correct 29 ms 9760 KB Output is correct
55 Correct 30 ms 9768 KB Output is correct
56 Correct 102 ms 9776 KB Output is correct
57 Correct 33 ms 10352 KB Output is correct
58 Correct 40 ms 10448 KB Output is correct
59 Correct 122 ms 10452 KB Output is correct
60 Correct 37 ms 11084 KB Output is correct
61 Correct 38 ms 11092 KB Output is correct
62 Correct 139 ms 11124 KB Output is correct
63 Correct 127 ms 11084 KB Output is correct
64 Correct 230 ms 11212 KB Output is correct
65 Correct 179 ms 11132 KB Output is correct
66 Correct 148 ms 11212 KB Output is correct
67 Correct 136 ms 11104 KB Output is correct
68 Correct 63 ms 11168 KB Output is correct
69 Correct 66 ms 11176 KB Output is correct
70 Correct 56 ms 11180 KB Output is correct
71 Correct 59 ms 11180 KB Output is correct
72 Incorrect 48 ms 11160 KB Output isn't correct
73 Incorrect 55 ms 11692 KB Output isn't correct
74 Correct 77 ms 11660 KB Output is correct
75 Correct 81 ms 11716 KB Output is correct
76 Correct 71 ms 11708 KB Output is correct
77 Correct 74 ms 11712 KB Output is correct
78 Correct 87 ms 11644 KB Output is correct
79 Correct 72 ms 11636 KB Output is correct
80 Correct 70 ms 11644 KB Output is correct
81 Correct 78 ms 11648 KB Output is correct
82 Correct 71 ms 11564 KB Output is correct
83 Correct 94 ms 11604 KB Output is correct
84 Correct 90 ms 11552 KB Output is correct
85 Correct 89 ms 11596 KB Output is correct
86 Correct 85 ms 11552 KB Output is correct
87 Correct 85 ms 11548 KB Output is correct
88 Correct 93 ms 11356 KB Output is correct
89 Correct 100 ms 11452 KB Output is correct
90 Correct 93 ms 11340 KB Output is correct
91 Correct 97 ms 11436 KB Output is correct
92 Correct 98 ms 11452 KB Output is correct