Submission #1007503

#	Time	Username	Problem	Language	Result	Execution time	Memory
1007503		huutuan	Mecho (IOI09_mecho)	C++14	100 / 100	141 ms	11904 KiB

mecho

#include <bits/stdc++.h>

using namespace std;

#define int long long

const int N=810, dx[]={1, -1, 0, 0}, dy[]={0, 0, 1, -1};
int n, s;
char a[N][N];
int d[N][N], f[N][N];
int xm, ym, xd, yd;

bool check(int t){
   queue<pair<int, int>> q;
   memset(f, 0x3f, sizeof f);
   q.emplace(xm, ym); f[xm][ym]=t*s;
   if ((f[xm][ym]+s)/s>d[xm][ym]) return 0;
   while (q.size()){
      int x=q.front().first, y=q.front().second; q.pop();
      if (x==xd && y==yd) return 1;
      for (int i=0; i<4; ++i){
         int u=x+dx[i], v=y+dy[i];
         if (u<1 || v<1 || u>n || v>n || f[u][v]<1e18 || (f[x][y]+s+1)/s>d[u][v] || a[u][v]=='T') continue;
         f[u][v]=f[x][y]+1;
         q.emplace(u, v);
      }
   }
   return 0;
}

int32_t main(){
   ios_base::sync_with_stdio(false);
   cin.tie(nullptr);
   cin >> n >> s;
   queue<pair<int, int>> q;
   memset(d, 0x3f, sizeof d);
   for (int i=1; i<=n; ++i) for (int j=1; j<=n; ++j){
      cin >> a[i][j];
      if (a[i][j]=='M') xm=i, ym=j;
      if (a[i][j]=='D') xd=i, yd=j;
      if (a[i][j]=='H'){
         d[i][j]=0;
         q.emplace(i, j);
      }
   }
   while (q.size()){
      int x=q.front().first, y=q.front().second; q.pop();
      for (int i=0; i<4; ++i){
         int u=x+dx[i], v=y+dy[i];
         if (u<1 || v<1 || u>n || v>n || d[u][v]<1e18 || a[u][v]=='T' || a[u][v]=='D') continue;
         d[u][v]=d[x][y]+1;
         q.emplace(u, v);
      }
   }
   check(234);
   int l=0, r=1e9;
   while (l<=r){
      int mid=(l+r)>>1;
      if (check(mid)) l=mid+1;
      else r=mid-1;
   }
   cout << r << '\n';
   return 0;
}

• Subtask 1: 100 / 100