Submission #682593

#	Time	Username	Problem	Language	Result	Execution time	Memory
682593		Ammar	Tracks in the Snow (BOI13_tracks)	C++17	21.56 / 100	756 ms	310580 KiB

tracks

#include <bits/stdc++.h>
#include<iostream>
#include<iomanip>
#include<algorithm>
#include<vector>
#include<utility>
#include<set>
#include<unordered_set>
#include<list>
#include<iterator>
#include<deque>
#include<queue>
#include<stack>
#include<set>
#include<bitset>
#include<random>
#include<map>
#include<unordered_map>
#include<stdio.h>
#include<complex>
#include<math.h>
#include<cstring>
#include<chrono>
#include<string>

// #pragma GCC optimize("Ofast")
// #pragma GCC optimize("no-stack-protector")
// #pragma GCC optimize("unroll-loops")
// #pragma GCC target("sse,sse2,sse3,ssse3,popcnt,abm,mmx,tune=native")
// #pragma GCC optimize("fast-math") 

using namespace std;
#define pb push_back
#define ff first
#define ss second
#define vi vector <int>
#define vvi vector <vi>
#define pii pair<int, int>
#define ppi pair<pii, int>
#define vii vector<pii>
#define mii map<int, int>
#define mci map<char, int>
#define miv map<int, vi>
#define mis map<int, set<int>>
#define setbits(n) __builtin_popcount(n)
#define all(v) (v).begin(), (v).end()
#define yes cout<<"YES"<<endl
#define no cout<<"NO"<<endl
#define endl "\n"
#define fo(i,n) for(int i=0;i<n;i++)
#define in(a,n)	for(int i=0;i<n;i++) cin>>a[i];
#define show2(a, b) cout<<a<<' '<<b<<endl
#define show3(a, b, c) cout<<a<<' '<<b<<' '<<c<<endl
#define show(arr) for (auto i:arr) cout<<i<<' '; 
#define Endl endl
const long long N=1e6+5;
const long long mod=1000000007; //998244353;
int n,m,sz;
vector<string> s;
vi dp;
int a[4005][4005],g[4005][4005];
int c[]={-1,0,0,1};
int d[]={0,-1,1,0};
bool inrange(int x, int y)
{
	return x>=0 && x<n && y>=0 && y<m;
}
void bfs(int i, int j)
{
	queue<pii> q;
	q.push(pii({i,j}));
	a[i][j]=sz;
	while(q.size())
	{
		auto p=q.front();q.pop();
		int x=p.ff,y=p.ss;
		for(int k=0;k<4;k++)
		{
			int u=x+c[k],v=y+d[k];
			if(inrange(u,v) && s[u][v]==s[i][j] && a[u][v]==-1)
			{
				q.push({u,v});a[u][v]=sz;
			}
		}
	}
	sz++;
}
void bfs2()
{
	queue<int> q;
	q.push(0);dp[0]=0;
	while(q.size())
	{
		int i=q.front();q.pop();
		// cout<<i<<endl;
		for(int j=0;j<sz;j++)
		{
			if(g[i][j] && dp[j]>1+dp[i])
			{
				dp[j]=1+dp[i];q.push(j);
			}
		}
	}
}
void cases(){
	cin>>n>>m;sz=0;
	s.clear();s.resize(n);in(s,n);
	memset(g,0,sizeof(g));
	memset(a,-1,sizeof(a));
	for(int i=0;i<n;i++)
	{
		for(int j=0;j<m;j++)
		{
			if(s[i][j]!='.' && a[i][j]==-1)
				bfs(i,j);
		}
	}
	dp.assign(sz,N);
	
	for(int i=0;i<n;i++)
	{
		for(int j=0;j<m;j++)
		{
			if(a[i][j]==-1)continue;
			int u=i+1,v=j+1;
			
			if(inrange(i,v) && a[i][v]!=a[i][j] && a[i][v]!=-1 )
			{
				g[a[i][v]][a[i][j]]=1;g[a[i][j]][a[i][v]]=1;
			}
			if(inrange(u,j) && a[i][j]!=a[u][j] && a[u][j]!=-1)
			{
				g[a[u][j]][a[i][j]]=1;g[a[i][j]][a[u][j]]=1;
			}
		}
	}
	// for(auto x:g)
	// {
		// show(x);cout<<endl;
	// }
	bfs2();
	int ans=0;
	for(auto x:dp)ans=max(ans,x+1);
	cout<<ans<<endl;
}

int32_t main(){
    std::ios::sync_with_stdio(false);
    cin.tie(NULL);cout.tie(NULL);
    int t=1;
    // cin>>t;
    for (int i=0; i<t; i++){
    	//cout<<"Case #"<<i+1<<": ";
		cases();
    }
    return 0;
}

• Subtask 1: 15 / 30
• Subtask 2: 6.5625 / 70