Re Rooting tree code example

Example: Re Rooting tree

#include<bits/stdc++.h>#define REP(i,n) for (int i = 1; i <= n; i++)#define mod 1000000007#define pb push_back#define ff first#define ss second#define ii pair<int,int>#define vi vector<int>#define vii vector<ii>#define lli long long int#define INF 1000000000#define endl '\n'const double PI = 3.141592653589793238460;typedef std::complex<double> Complex;typedef std::valarray<Complex> CArray;using namespace std; vi ar[200001];lli res[200001];int subSize[200001];lli subDist[200001];int n; void dfs1(int node , int par){	subSize[node] = 1;		for(int child : ar[node])	if(child != par)	{		dfs1(child , node);		subSize[node] += subSize[child];				subDist[node] += subSize[child] + subDist[child];	}} void dfs(int node , int par){	res[node] = res[par] - subSize[node] - subDist[node] + n - subSize[node] + subDist[node];		for(int child : ar[node])	if(child != par)	dfs(child , node);} int main(){	int a , b;	cin>>n;	REP(i , n-1) cin>>a>>b , ar[a].pb(b) , ar[b].pb(a);		dfs1(1 , -1);	res[1] = subDist[1];		for(int child : ar[1])	dfs(child , 1);		REP(i , n) cout<<res[i]<<" ";}