Submission #742712

#	Time	Username	Problem	Language	Result	Execution time	Memory
742712		airths	Mecho (IOI09_mecho)	C++17	39 / 100	516 ms	16780 KiB

mecho

/*
 * 
 * 	^v^
 * 
 */
#include <iostream>
#include <string>
#include <cmath>
#include <vector>
#include <iomanip>
#include <map>
#include <numeric>
#include <functional>
#include <algorithm>
#include <set>
#include <queue>
#include <climits>
#include <cstdlib>
#include <chrono>
// #include <ext/pb_ds/assoc_container.hpp>
// #include <ext/pb_ds/tree_policy.hpp>
// using namespace __gnu_pbds;
using namespace std;
// #define ordered_set tree<ll, null_type, less<ll>, rb_tree_tag, tree_order_statistics_node_update>
#define iamtefu ios_base::sync_with_stdio(false); cin.tie(0);
#define ll long long int
#define ld long double
#define sc(a) scanf("%lld", &a);
#define scv(a, n) vector<ll> a(n);fl(i,0,n){sc(a[i])}
#define prl(a) fl(i,0,a.size()){printf("%lld ", a[i]);}printf("\n");
#define fl(i,a,n) for (ll i(a); i<n; i++)
#define rfl(i,a,n) for (ll i(n-1); i>=a; i--)
#define print(a) for (auto x:a){cout<<x<<" ";} cout<<"\n";
#define tt int tt; cin>>tt; for(;tt--;)
ll gcd(ll a, ll b){
	if (b==0){
		return a;
	}
	return gcd(b, a%b);
}
ll pw(ll a, ll b, ll m){
	ll res=1;
	a%=m;
	while (b){
		if (b&1){
			res=(res*a)%m;
		}
		a=(a*a)%m;
		b/=2;
	}
	return res;
}
void scn(){
	ll n, s; cin>>n>>s;
	vector <string> c(n);
	vector <vector <ll>> a(n+1, vector <ll>(n+1, 1e9));
	queue <vector <ll>> q;
	fl(i,0,n){
		cin>>c[i];
		fl(j,0,n){
			if (c[i][j]=='H'){
				q.push({i, j});
				a[i][j]=0;
			}
		}
	}
	vector <ll> di={1, 1, 0, -1, -1, -1, 0, 1};
	vector <ll> dj={0, 1, 1, 1, 0, -1, -1, -1};
	while (!q.empty()){
		auto j = q.front();
		q.pop();
		for (int d=0; d<8; d+=2){
			ll i1 = j[0]+di[d], j1 = j[1]+dj[d];
			if (i1>=0 && j1>=0 && i1<n && j1<n && a[i1][j1]==1e9 && (c[i1][j1]=='G' || c[i1][j1]=='M')){
				q.push({i1, j1});
				a[i1][j1]=a[j[0]][j[1]]+1;
			}
		}
	}
	vector <vector <ll>> dis(n+1, vector <ll>(n+1, 1e9));
	vector <ll> hij;
	fl(i,0,n){
		fl(j,0,n){
			if (c[i][j]=='M'){
				q.push({i, j});
				dis[i][j]=0;
				hij={i, j};
			}
		}
	}
	while (!q.empty()){
		auto j = q.front();
		q.pop();
		for (int d=0; d<8; d+=2){
			ll i1 = j[0]+di[d], j1 = j[1]+dj[d];
			if (i1>=0 && j1>=0 && i1<n && j1<n && dis[i1][j1]==1e9 && (c[i1][j1]=='G' || c[i1][j1]=='D')){
				dis[i1][j1]=dis[j[0]][j[1]]+1;
				q.push({i1, j1});
			}
		}
	}
	for (auto &y:dis){
		for (auto &x:y){
			if (x!=1e9){
				x=(x+s-1)/s;
			}
		}
	}
	if (a[hij[0]][hij[1]]==0){
		cout<<"-1\n";
		return;
	}
	// for (auto x:dis){
	// 	print(x)
	// }
	// cout<<'\n';
	// for (auto x:a){
	// 	print(x)
	// }
	auto ist=[&](ll mid){
		vector <vector <ll>> vis(n+1, vector <ll>(n+1));
		queue <vector <ll>> q;
		q.push({hij[0], hij[1], s});
		while (!q.empty()){
			auto j = q.front();
			q.pop();
			if (c[j[0]][j[1]]=='D'){
				return true;
			}
			if (j[2]==0 && dis[j[0]][j[1]]+mid>=a[j[0]][j[1]]){
				// cout<<dis[j[0]][j[1]]<<" "<<mid<<" "<<a[j[0]][j[1]]<<"  pl1\n";
				continue;
			} else if (j[2] && dis[j[0]][j[1]]+mid-1>=a[j[0]][j[1]]){
				continue;
			}
			// cout<<c[j[0]][j[1]]<<"  pl\n";
			for (int d=0; d<8; d+=2){
				ll i1 = j[0]+di[d], j1 = j[1]+dj[d];
				if (i1>=0 && i1<n && j1>=0 && j1<n && (c[i1][j1]=='D' || c[i1][j1]=='G') && vis[i1][j1]==0){
					q.push({i1, j1, (j[2]==0?s-1:j[2]-1)});
					vis[i1][j1]++;
				}
			}
		}
		return false;
	};
	ll l = 0, r = n+1;
	// cout<<ist(3)<<"  o\n";
	while (l<=r){
		// cout<<l<<" "<<r<<'\n';
		ll mid = (l+r)/2;
		// cout<<mid<<" "<<ist(mid)<<"  pl\n";
		if (ist(mid)){
			l = mid+1;
		} else {
			r = mid-1;
		}
	}
	if (ist(0)==0){
		cout<<"-1\n";
		return;
	}
	cout<<max(0ll,l-1)<<'\n';

	// not necessarily distinct
}
int main(){
	iamtefu;
#if defined(airths)
	auto t1=chrono::high_resolution_clock::now();
	freopen("input.txt", "r", stdin);
	freopen("output.txt", "w", stdout);
#else
	//
#endif
	// tt
	{
		scn();
	}
#if defined(airths)
	auto t2=chrono::high_resolution_clock::now();
	ld ti=chrono::duration_cast<chrono::nanoseconds>(t2-t1).count();
	ti*=1e-6;
	cerr<<"Time: "<<setprecision(12)<<ti;
	cerr<<"ms\n";
#endif
	return 0;
}

• Subtask 1: 39 / 100