Submission #491225

#	Time	Username	Problem	Language	Result	Execution time	Memory
491225		tar_palantir	Beads and wires (APIO14_beads)	C++17	100 / 100	179 ms	29100 KiB

beads

// INCOMPLETE

#include<bits/stdc++.h>
#define int     long long
#define task    "beads"
using namespace std;
using ii=pair<int,int>;

const int mn=2e5+11,inf=0x3f3f3f3f3f3f3f3f;
const int mk=111;

int n;
vector<ii>adj[mn];

template<typename _t>
bool ckmax(_t& target,const _t& source){
	return target<source ? target=source, 1 : 0;
}

int dp[mn][4];
void dfs(int u,int pre){
	vector<int>mval(5,-inf);
	for(const ii& k:adj[u]){
		int v=k.first,w=k.second;
		if(v==pre)continue;
		
		dfs(v,u);
	
		int eval=max(dp[v][0],dp[v][2]+w);
		dp[u][0]+=eval;
		
		ckmax(mval[4],max(dp[v][1],dp[v][3]+w)-eval);
		ckmax(mval[1],max(mval[2]+max(dp[v][0],dp[v][1])+w,mval[3]+dp[v][0]+w)-eval);
		
		ckmax(mval[2],dp[v][0]+w-eval);
		ckmax(mval[3],dp[v][1]+w-eval);
	}
	
	dp[u][1]=dp[u][0]+max(mval[1],mval[4]);
	dp[u][2]=dp[u][0]+mval[2];
	dp[u][3]=dp[u][0]+mval[3];
}

int32_t main()
{
    cin.tie(0)->sync_with_stdio(0);

    cin>>n;
    for(int i=1,u,v,w;i<n;i++){
    	cin>>u>>v>>w;
    	adj[u].emplace_back(v,w);
    	adj[v].emplace_back(u,w);
    }
    
    dfs(1,-1);
    cout<<max(dp[1][0],dp[1][1]);
}

• Subtask 1: 13 / 13
• Subtask 2: 15 / 15
• Subtask 3: 29 / 29
• Subtask 4: 43 / 43