Submission #158441

#	Time	Username	Problem	Language	Result	Execution time	Memory
158441		arnold518	Beads and wires (APIO14_beads)	C++14	0 / 100	6 ms	4984 KiB

beads

#include <bits/stdc++.h>
using namespace std;

typedef long long ll;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;

const int MAXN = 2e5;

int N;
vector<pii> adj[MAXN+10];
ll dp1[MAXN+10], dp2[MAXN+10];

void dfs(int now, int bef, int par)
{
    vector<ll> V;
    ll S=0;
    for(pii nxt : adj[now])
    {
        if(nxt.first==bef) continue;
        dfs(nxt.first, now, nxt.second);
        S+=max(dp1[nxt.first], dp2[nxt.first]);
        V.push_back(dp2[nxt.first]+nxt.second-max(dp1[nxt.first], dp2[nxt.first]));
    }
    sort(V.begin(), V.end(), greater<ll>());
    dp2[now]=S;

    if(V.size()>1 && V[0]+V[1]>=0) dp2[now]+=V[0]+V[1];

    if(V.size()<=0) dp1[now]=-987654321987654321;
    else dp1[now]=S+par+V[0];

    //printf("%d %lld %lld\n", now, dp1[now], dp2[now]);
}

int main()
{
    int i, j;

    scanf("%d", &N);
    for(i=1; i<N; i++)
    {
        int u, v, w;
        scanf("%d%d%d", &u, &v, &w);
        adj[u].push_back({v, w});
        adj[v].push_back({u, w});
    }

    dfs(1, 1, 0);
    printf("%lld", dp2[1]);
}

Compilation message (stderr)

beads.cpp: In function 'int main()':
beads.cpp:38:12: warning: unused variable 'j' [-Wunused-variable]
     int i, j;
            ^
beads.cpp:40:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
     scanf("%d", &N);
     ~~~~~^~~~~~~~~~
beads.cpp:44:14: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
         scanf("%d%d%d", &u, &v, &w);
         ~~~~~^~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 0 / 13
• Subtask 2: 0 / 15
• Subtask 3: 0 / 29
• Subtask 4: 0 / 43