Submission #953194

#	Time	Username	Problem	Language	Result	Execution time	Memory
953194		tmtxangel	Mecho (IOI09_mecho)	C++17	10 / 100	115 ms	7000 KiB

mecho

#include <bits/stdc++.h>


#define lli long long
#define ld long double
#define tmt angel

using namespace std;
const int maxn = 802;
int vis[maxn][maxn], n, m;
char a[maxn][maxn];
int tim[maxn][maxn];
int hi, hj, sti, stj;
int x[4] = {1, -1, 0, 0};
int y[4] = {0, 0, 1, -1};
deque<pair<pair<int, int>, int>> s;
bool flag = false;

void gocheck(int i, int j, int cost)
{
    if(i < 1 || j < 1 || i > n || j > n || vis[i][j] == 1 || a[i][j] == 'D') return;
    vis[i][j] = 1;
    tim[i][j] = cost;
    s.push_back({{i, j}, cost});
}
void spread(int i, int j, int cost, int step)
{
    if(vis[hi][hj] == 1) return;
    if(i < 1 || j < 1 || i > n || j > n || vis[i][j] == 1 || tim[i][j] < cost) return;
    vis[i][j] = 1;
   //     cout << i << " " << j << " " << cost << " " << step << '\n';
    if(vis[hi][hj] == 1) return;
    if(step == m)
    {
        //tim[1][i][j] = cost;
        s.push_back({{i, j}, cost});
    }
    else
    {
       // tim[1][i][j] = cost;
          for(int f = 0; f < 4; f++)
          {
             spread(i + x[f], j + y[f], cost, step + 1);
            if(vis[hi][hj] == 1) break;
          }
    }
}

void Bfs()
{
    while(!s.empty())
    {
        int i = s.front().first.first;
        int j = s.front().first.second;
        int c = s.front().second;
        s.pop_front();
        for(int f = 0; f < 4; f++)
        {
            gocheck(i + x[f], j + y[f], c+1);
        }
    }
}

bool checked(int st)
{
    s.clear();
    flag = false;
   // if(st == 0) s.push_back({ {sti, stj},{2, 0} });
    for(int i = 1; i <= n; i++)
    {
    for(int j = 1; j <= n; j++)
    {
        vis[i][j] = a[i][j] == 'G' || a[i][j] == 'D' ? 0 : 1;
    }
    }
    s.push_back({{sti, stj}, st});
    while(!s.empty() && vis[hi][hj] == 0)
    {
         int i = s.front().first.first;
        int j = s.front().first.second;
        int c = s.front().second;
        s.pop_front();
        for(int f = 0; f < 4; f++)
        {
            spread(i + x[f], j + y[f], c+1, 1);
            if(vis[hi][hj] == 1) break;
        }
    }
       return vis[hi][hj] == 1;

}

int main()
{
  ios_base::sync_with_stdio(false);
  cin.tie(nullptr);
//   freopen(".INP", "r" , stdin);
//   freopen(".OUT", "w" , stdout);
cin >> n >> m;
for(int i = 1; i <= n; i++)
{
    for(int j = 1; j <= n; j++)
    {
        cin >> a[i][j];
        if(a[i][j] == 'M')
        {
            vis[i][j] = 1;
            sti = i;
            stj = j;
        }
        else vis[i][j] = a[i][j] == 'G' ? 0 : 1;
        if(a[i][j] == 'D')
        {
            hi = i;
            hj = j;
        }
        if(a[i][j] == 'H')
        {
            s.push_back({{i, j}, 0});
            vis[i][j] = 1;
        }
    }
}
Bfs();
tim[hi][hj] = 1e18;
 //cout << checked(1);
int low = 0, high = n, mid;
while(low <= high)
{
    mid = (low + high) / 2;
    if(checked(mid)) low = mid+1;
    else high = mid - 1;
}
cout << high;

return 0;
}

Compilation message (stderr)

mecho.cpp: In function 'int main()':
mecho.cpp:125:15: warning: overflow in conversion from 'double' to 'int' changes value from '1.0e+18' to '2147483647' [-Woverflow]
  125 | tim[hi][hj] = 1e18;
      |               ^~~~

• Subtask 1: 10 / 100