Hackerrank-cut the Tree

Typical tree recursion works. The key Is:any node can be treated as the root, since it was about edge and not on node. This simplifies things a lot.

#include <cmath>#include<cstdio>#include<vector>#include<iostream>#include<algorithm>#include<unordered_set>using namespaceStd;typedefLong Longlong64;structnode{Node (): Val (0{} Node (unsigned v): Val (v) {} long64 val; Unordered_set<int>Inx;}; LONG64 ret= std::numeric_limits<unsigned>:: Max (); long64 Go (Vector<Node> &nodes,introot, long64 tsum) {Node&n =Nodes[root]; long64 Currsum=N.val;  for(intI:n.inx)        {nodes[i].inx.erase (root); Currsum+=Go (nodes, I, tsum); } ret= Std::min (Std::abs (Tsum-2*currsum), ret); returncurrsum;}intMain () {intN CIN >>N; Vector<Node>nodes (n); long64 sum=0;  for(inti =0; I < n; i++) {unsigned v; CIN>>v; Sum+=v; Nodes[i].val=v; }     for(inti =0; I < n-1; i++)    {        intPi, CI; Cin >> Pi >>CI; Nodes[pi-1].inx.insert (CI-1); Nodes[ci-1].inx.insert (PI-1); } Go (nodes,0, sum); cout<< ret <<Endl; return 0;}

Hackerrank-cut the Tree