Submission #227775

#	Time	Username	Problem	Language	Result	Execution time	Memory
227775		MohamedAhmed04	Dostavljač (COCI18_dostavljac)	C++14	14 / 140	2092 ms	2552 KiB

dostavljac

#include <bits/stdc++.h>

using namespace std ;

const int MAX = 500 + 10 ;

int arr[MAX] , in[MAX] , out[MAX] , nxt[MAX+MAX] ;
int dp[MAX+MAX][MAX] ;
int n , m ;
vector< vector<int> >adj(MAX) ;
vector<int>eul ;

void dfs(int node , int par)
{
	in[node] = eul.size() ;
	eul.push_back(node) ;
	for(auto &child : adj[node])
	{
		if(child == par)
			continue ;
		dfs(child , node) ;
		nxt[in[child]] = eul.size() ;
		eul.push_back(node) ;
	}
	out[node] = eul.size()-1 ;
	return ;
}

int solve(int idx, int rem)
{
	if(idx == eul.size())
		return -1e9 ;
	if(rem == 0)
	{
		if(eul[idx] == 1)
			return 0 ;
		else
			return -1e9 ;
	}
	int &ret = dp[idx][rem] ;
	if(ret != -1)
		return ret ;
	int node = eul[idx] ;
	//fourth choice
	ret = -1e9 ;
	if(node == 1)
		ret = 0 ;
	/* 4 choices
	First choice is to buy and stop
	Second choice is to buy and continue
	third choice is to continue and not buying
	Fourth choice is stop*/
	if(in[node] == idx)
	{
		// first choice
		if(node == 1)
			ret = max(ret , arr[node]) ;
		// second choice
		/* 2 choices
		Go to the next node
		Go to the next subtree if next node is still my child
		*/
		if(rem >= 2)
			ret = max(ret , solve(idx+1 , rem-2) + arr[node]) ;
		int to = -1 ;
		if(idx < eul.size()-1)
			to = eul[idx+1] ;
		if(to != -1 && in[to] >= in[node] && out[to] <= out[node])
			ret = max(ret , solve(nxt[idx+1] , rem-1) + arr[node]) ;
	}
	//third choice
	ret = max(ret , solve(idx+1 , rem-1)) ;
	int to = -1 ;
	if(idx < eul.size()-1)
		to = eul[idx+1] ;
	if(to != -1 && in[to] >= in[node] && out[to] <= out[node])
		ret = max(ret , solve(nxt[idx+1] , rem)) ;
	return ret ;
}

int main()
{
	memset(dp , -1 , sizeof(dp)) ;
	ios_base::sync_with_stdio(0) ;
	cin.tie(0) ;
	cin>>n>>m ;
	for(int i = 1 ; i <= n ; ++i)
		cin>>arr[i] ;
	for(int i = 0 ; i < n-1 ; ++i)
	{
		int x , y ;
		cin>>x>>y ;
		adj[x].push_back(y) ;
		adj[y].push_back(x) ;
	}
	int ans = 0 ;
	for(int i = 1 ; i <= n ; ++i)
	{
		eul.clear() ;
		dfs(i , -1) ;
		memset(dp , -1 , sizeof(dp)) ;
		ans = max(ans , solve(0 , m)) ;
	}
	return cout<<ans<<"\n" , 0 ;
}		

Compilation message (stderr)

dostavljac.cpp: In function 'int solve(int, int)':
dostavljac.cpp:31:9: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  if(idx == eul.size())
     ~~~~^~~~~~~~~~~~~
dostavljac.cpp:66:10: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   if(idx < eul.size()-1)
      ~~~~^~~~~~~~~~~~~~
dostavljac.cpp:74:9: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  if(idx < eul.size()-1)
     ~~~~^~~~~~~~~~~~~~

• Subtask 1: 14 / 14
• Subtask 2: 0 / 14
• Subtask 3: 0 / 14
• Subtask 4: 0 / 14
• Subtask 5: 0 / 14
• Subtask 6: 0 / 14
• Subtask 7: 0 / 14
• Subtask 8: 0 / 14
• Subtask 9: 0 / 14
• Subtask 10: 0 / 14