Submission #1012857

#	Time	Username	Problem	Language	Result	Execution time	Memory
1012857		EkinOnal	Mecho (IOI09_mecho)	C++17	100 / 100	487 ms	12528 KiB

mecho

//#pragma GCC optimize("O3,unroll-loops,Ofast")
//#pragma GCC target("avx2,bmi,bmi2,popcnt,lzcnt")
#include <bits/stdc++.h>
//#include <cstdio>
//#include <iostream>
using namespace std;
 
#define MAX 100000007
#define pb push_back
//#define mp make_pair 
#define int long long
#define f first
#define s second
#define vi vector<int>
#define pii pair<int,int>
#define si set<int>
#define vpii vector<pair<int,int>> 
const int mod = 1e9+7;
const int INF = 1e18;
// myMap.begin()->first :  key
// myMap.begin()->second : value
 
int epow(int a,int b){int ans=1;while(b){if(b&1) ans*=a;a*=a;ans%=mod;a%=mod;b>>=1;}return ans%mod;}
int gcd(int a,int b) {if(a<b)swap(a,b);while(b){int tmp=b;b=a%b;a=tmp;}return a;}
int mul(int a,int b){return ((a%mod)*(b%mod))%mod;}


int dx[] = {-1, 0, 1, 0};
int dy[] = {0, -1, 0, 1};


int n,s;
vector<vector<char>> grid(1000,vector<char>(1000));
bool valid_sq(int x, int y) {
	return x >= 0 && x < n && y >= 0 && y < n &&
	       (grid[x][y] == 'G' || grid[x][y] == 'M');
}

bool mecho_reached(int mecho_dis, int bees_dis) {
	return mecho_dis / s < bees_dis;
}




void solve() {
	cin >> n >> s;

	pii bear,home;
	vector<pii> hives;
	for(int i=0;i<n;i++)
	{
		for(int j=0;j<n;j++)
		{
			cin >> grid[i][j];
			if(grid[i][j]=='H') hives.pb({i,j});
			if(grid[i][j]=='M') bear = {i,j};
			if(grid[i][j]=='D') home = {i,j};
		}
	}


	int l=0,r=n*n;
	while(l<=r)
	{
		vector<vector<int>> d(n+2,vector<int>(n+2,INF));
		queue<pii> q;
		for(int i=0;i<hives.size();i++)
		{
			q.push({hives[i]});
			d[hives[i].f][hives[i].s]=0;
		}	

		while(q.size())
		{
			int x = q.front().first, y = q.front().second;
			q.pop();
			for (int i=0;i<4;i++)
			{
				int nx = x + dx[i], ny = y + dy[i];
				if (valid_sq(nx, ny) && d[nx][ny]==INF) 
				{
					d[nx][ny] = d[x][y] + 1;
					q.push({nx, ny});
				}
			}
		}



		int time = (l+r)/2;

	//	queue<pii> q; 
		q = queue<pii>();
		vector<vi> dbear(n+2,vi(n+2,INF));

		q.push(bear);
		dbear[bear.f][bear.s]=0;

		if(d[bear.f][bear.s]<=time) q.pop();

		while(q.size())
		{
			int x = q.front().first, y = q.front().second;
			q.pop();
			for (int i=0;i<4;i++)
			{
				int nx=x+dx[i],ny=y+dy[i];
				if (valid_sq(nx, ny) && dbear[nx][ny]==INF  &&mecho_reached(dbear[x][y]+1,d[nx][ny]-time)) 
				{
					q.push({nx, ny});
					dbear[nx][ny] = dbear[x][y] + 1;
				}
			}
		}


		bool flag = false;
		for (int i = 0; i < 4; i++) 
		{
			int nx = home.f + dx[i], ny = home.s + dy[i];
			if (valid_sq(nx, ny) &&mecho_reached(dbear[nx][ny],d[nx][ny]-time) && dbear[nx][ny]!=INF) flag = true;
		}
		if (flag) l = time + 1;
		else  r = time - 1;


	}
	cout << l-1 << endl;

    return;
}	


int32_t main() {
//	freopen("lasers.in", "r", stdin);
//	freopen("lasers.out", "w", stdout);
	std::ios_base::sync_with_stdio(false);
    std::cin.tie(nullptr);

    int t=1;
 //   cin >> t;
    while (t--) solve();

    return 0;
}

Compilation message (stderr)

mecho.cpp: In function 'void solve()':
mecho.cpp:68:16: 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]
   68 |   for(int i=0;i<hives.size();i++)
      |               ~^~~~~~~~~~~~~

• Subtask 1: 100 / 100