Submission #697764

#	Time	Username	Problem	Language	Result	Execution time	Memory
697764		vjudge1	Beads and wires (APIO14_beads)	C++17	100 / 100	115 ms	17008 KiB

beads

#include<bits/stdc++.h>
using namespace std;
const int N=2e5+10;
struct edge{
    int w,to,nxt;
};
edge ed[N<<1];
int cnt,h[N];
void add(int st,int et,int wi){
    cnt++;
    ed[cnt].to=et;
    ed[cnt].w=wi;
    ed[cnt].nxt=h[st];
    h[st]=cnt;
}
int sum[N][3],dp[N][3][2],n;
void dfs(int x,int fa){
    sum[x][0]=0;
    dp[x][0][0]=0;
    for(int i=h[x];i;i=ed[i].nxt){
        int v=ed[i].to;
        if(v==fa)continue;
        dfs(v,x);
        dp[x][2][1]=max({dp[x][2][1]+max(dp[v][1][0]+ed[i].w,dp[v][0][0]),dp[x][1][0]+ed[i].w+max(sum[v][2],dp[v][0][1]),dp[x][1][1]+ed[i].w+dp[v][0][0]});
        dp[x][2][0]=max({dp[x][2][0]+max(dp[v][1][0]+ed[i].w,dp[v][0][0]),dp[x][1][0]+ed[i].w+dp[v][0][0]});
        dp[x][1][1]=max({dp[x][1][1]+max(dp[v][1][0]+ed[i].w,dp[v][0][0]),dp[x][0][0]+ed[i].w+max(sum[v][2],dp[v][0][1])});
        dp[x][1][0]=max({dp[x][1][0]+max(dp[v][1][0]+ed[i].w,dp[v][0][0]),dp[x][0][0]+ed[i].w+dp[v][0][0]});
        dp[x][0][1]=max({dp[x][0][1]+max(dp[v][1][0]+ed[i].w,dp[v][0][0]),dp[x][0][0]+max({ed[i].w+dp[v][1][1],sum[v][2],dp[v][0][1]})});
        dp[x][0][0]=dp[x][0][0]+max(dp[v][1][0]+ed[i].w,dp[v][0][0]);
    }
    sum[x][0]=max(dp[x][0][0],dp[x][0][1]);
    sum[x][1]=max(dp[x][1][0],dp[x][1][1]);
    sum[x][2]=max(dp[x][2][0],dp[x][2][1]);
}
int main(){
    scanf("%d",&n);
    for(int i=1,x,y,w;i<n;i++){
        scanf("%d%d%d",&x,&y,&w);
        add(x,y,w);
        add(y,x,w);
    }
    memset(dp,-63,sizeof dp);
    memset(sum,-63,sizeof sum);
    dfs(1,0);
    printf("%d",max(sum[1][0],sum[1][2]));
    return 0;
}

Compilation message (stderr)

beads.cpp: In function 'int main()':
beads.cpp:36:10: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   36 |     scanf("%d",&n);
      |     ~~~~~^~~~~~~~~
beads.cpp:38:14: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   38 |         scanf("%d%d%d",&x,&y,&w);
      |         ~~~~~^~~~~~~~~~~~~~~~~~~

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