51nod 1405 树的距离之和 树形dp

#pragma comment(linker, "/STACK:1024000000,1024000000")
#include<iostream>
#include<cstdio>
#include<cmath>
#include<string>
#include<queue>
#include<algorithm>
#include<stack>
#include<cstring>
#include<vector>
#include<list>
#include<bitset>
#include<set>
#include<map>
#include<time.h>
using namespace std;
#define LL long long
#define bug(x)  cout<<"bug"<<x<<endl;
const int N=1e5+10,M=1e6+10,inf=1e9+10,MOD=1e9+7;
const LL INF=1e18+10,mod=1e9+7;
const double eps=(1e-8),pi=(4*atan(1.0));

struct is
{
    int v,nex;
}edge[N<<1];
int head[N],edg;
void add(int u,int v)
{
    edge[++edg]=(is){v,head[u]};
    head[u]=edg;
}
LL ans[N],a[N];
int si[N];
void dfs(int u,int fa)
{
    si[u]=1;
    for(int i=head[u];i;i=edge[i].nex)
    {
        int v=edge[i].v;
        if(v==fa)continue;
        dfs(v,u);
        si[u]+=si[v];
        a[u]+=a[v]+si[v];
    }
}
int n;
void dfs2(int u,int fa,LL now)
{
    ans[u]=a[u]+now;
    for(int i=head[u];i;i=edge[i].nex)
    {
        int v=edge[i].v;
        if(v==fa)continue;
        dfs2(v,u,now+a[u]-a[v]-si[v]+n-si[v]);
    }
}
int main()
{
    scanf("%d",&n);
    for(int i=1;i<n;i++)
    {
        int u,v;
        scanf("%d%d",&u,&v);
        add(u,v);add(v,u);
    }
    dfs(1,0);
    dfs2(1,0,0);
    for(int i=1;i<=n;i++)
        printf("%lld\n",ans[i]);
    return 0;
}