标签:second dfs pre class push its sig false i++
每个点有重数,求到所有点距离最小的点
就是魔改的重心了
#include <bits/stdc++.h>
using namespace std;
#define int long long
const int N = 1000005;
vector <pair<int,int> > g[N];
int siz[N],f[N],vis[N],sum[N],c[N],n,m,t1,t2,t3,tot;
void dfs1(int p) {
vis[p]=1;
siz[p]=c[p];
for(int i=0;i<g[p].size();i++) {
int q=g[p][i].first, w=g[p][i].second;
if(vis[q]==0) {
dfs1(q);
sum[p]+=sum[q]+siz[q]*w;
siz[p]+=siz[q];
}
}
}
void dfs2(int p) {
vis[p]=1;
for(int i=0;i<g[p].size();i++) {
int q=g[p][i].first, w=g[p][i].second;
if(vis[q]==0) {
f[q] = f[p] - siz[q]*w + (tot-siz[q])*w;
dfs2(q);
}
}
}
signed main() {
ios::sync_with_stdio(false);
cin>>n;
for(int i=1;i<=n;i++) cin>>c[i], tot+=c[i];
for(int i=1;i<n;i++) {
cin>>t1>>t2>>t3;
g[t1].push_back(make_pair(t2,t3));
g[t2].push_back(make_pair(t1,t3));
}
dfs1(1);
memset(vis,0,sizeof vis);
f[1]=sum[1];
dfs2(1);
int ans = 1e+18;
for(int i=1;i<=n;i++) {
ans = min(ans, f[i]);
}
cout<<ans<<endl;
}
标签:second dfs pre class push its sig false i++
原文地址:https://www.cnblogs.com/mollnn/p/12264634.html