#include <bits/stdc++.h>
#define gibon ios::sync_with_stdio(false); cin.tie(0);
#define bp __builtin_popcount
#define fir first
#define sec second
#define pii pair<int, int>
#define pll pair<ll, ll>
#pragma GCC optimize("O3")
#pragma GCC optimize("Ofast")
#pragma GCC optimize("unroll-loops")
typedef long long ll;
using namespace std;
int dx[4]={0, 1, 0, -1}, dy[4]={1, 0, -1 , 0};
const int mxN=200010;
const int mxM=7300000;
const int mxK=100001;
const int MOD=1000000007;
const ll INF=9223372036854775807;
int N;
vector <pii> v[mxN];
vector <pii> adj[mxN];
ll par[mxN];
ll dp1[mxN], dp2[mxN];
typedef struct cmp1{
bool operator()(ll a, ll b)
{
return a>b;
}
}cmp1;
void dfs0(int now, int pre)
{
for(pii nxt : v[now]) if(nxt.fir!=pre)
{
dfs0(nxt.fir, now);
adj[now].push_back(nxt);
par[nxt.fir]=nxt.sec;
}
}
void dfs1(int now)
{
priority_queue <ll, vector<ll>, cmp1> pq;
ll sum1=0;
for(pii nxt : adj[now])
{
dfs1(nxt.fir);
}
for(pii nxt : adj[now])
//printf("dp1[%d]=%lld, dp2[%d]=%lld\n", nxt.fir, dp1[nxt.fir], nxt.fir, dp2[nxt.fir]);
sum1+=dp1[nxt.fir];
pq.push(dp2[nxt.fir]+nxt.sec-dp1[nxt.fir]);
}
while(pq.size()>2) pq.pop();
ll tmp1, tmp2;
if(adj[now].empty())
{
dp1[now]=dp2[now]=0;
return;
}
if(adj[now].size()==1)
{
dp2[now]=sum1;
dp1[now]=max(dp2[now], sum1+par[now]+pq.top());
return;
}
tmp1=pq.top();
pq.pop();
tmp2=pq.top();
pq.pop();
//printf("tmp1=%lld, tmp2=%lld\n", tmp1, tmp2);
dp2[now]=sum1+max((ll)0, tmp1+tmp2);
dp1[now]=max(dp2[now], sum1+par[now]+tmp2);
}
int main()
{
gibon
cin >> N;
for(int i=1;i<N;i++)
{
int a, b, c;
cin >> a >> b >> c;
v[a].push_back({b, c});
v[b].push_back({a, c});
}
dfs0(1, -1);
dfs1(1);
cout << dp2[1];
}
Compilation message
beads.cpp: In function 'void dfs1(int)':
beads.cpp:47:5: warning: this 'for' clause does not guard... [-Wmisleading-indentation]
47 | for(pii nxt : adj[now])
| ^~~
beads.cpp:50:9: note: ...this statement, but the latter is misleadingly indented as if it were guarded by the 'for'
50 | pq.push(dp2[nxt.fir]+nxt.sec-dp1[nxt.fir]);
| ^~
beads.cpp:50:21: error: 'nxt' was not declared in this scope
50 | pq.push(dp2[nxt.fir]+nxt.sec-dp1[nxt.fir]);
| ^~~
beads.cpp: At global scope:
beads.cpp:52:5: error: expected unqualified-id before 'while'
52 | while(pq.size()>2) pq.pop();
| ^~~~~
beads.cpp:54:5: error: expected unqualified-id before 'if'
54 | if(adj[now].empty())
| ^~
beads.cpp:59:5: error: expected unqualified-id before 'if'
59 | if(adj[now].size()==1)
| ^~
beads.cpp:65:5: error: 'tmp1' does not name a type
65 | tmp1=pq.top();
| ^~~~
beads.cpp:66:5: error: 'pq' does not name a type
66 | pq.pop();
| ^~
beads.cpp:67:5: error: 'tmp2' does not name a type
67 | tmp2=pq.top();
| ^~~~
beads.cpp:68:5: error: 'pq' does not name a type
68 | pq.pop();
| ^~
beads.cpp:70:5: error: 'dp2' does not name a type
70 | dp2[now]=sum1+max((ll)0, tmp1+tmp2);
| ^~~
beads.cpp:71:5: error: 'dp1' does not name a type
71 | dp1[now]=max(dp2[now], sum1+par[now]+tmp2);
| ^~~
beads.cpp:72:1: error: expected declaration before '}' token
72 | }
| ^
