Best Coder Round#25 1003 树的非递归访问

/**
 * For best-coder problem 3
 */
#include <iostream>
using namespace std;

#include <set>
#include <stack>

struct Node
{
public:
    Node() :mIsVisited(false) {}

    bool mIsVisited;
    set< int > mChilds;
    set< int > mColorSet;
};

int main()
{
    int nNode, nCounting;
    while( cin >> nNode >> nCounting )
    {
        Node node[50001];

        int edge[50001][2];
        for( int i=1; i<nNode; i++ )
        {
            int a, b;
            cin >> a >> b;
            node[a].mChilds.insert(b);
            node[b].mChilds.insert(a);
        }

        for( int i=0; i<nCounting; i++ )
        {
            int n, color;
            cin >> n >> color;
            node[n].mColorSet.insert(color);
        }

        stack<int> nodeStack;

        node[1].mIsVisited = true;
        nodeStack.push(1);

        do{
           int currentTop = nodeStack.top();
           Node& topNode = node[currentTop];

           set<int> & topChilds = topNode.mChilds;
           set<int> & topColors = topNode.mColorSet;

           for( set<int>::iterator ci = topChilds.begin();
                ci != topChilds.end();
                ci++ )
           {
               int child = *ci;
               if( node[child].mIsVisited )
               {
                   topChilds.erase(child);
                   continue;
               }

               node[child].mIsVisited = true;
               nodeStack.push(child);
               break;
           }

           // it‘s a leaf child
           if( topChilds.empty() )
           {
               nodeStack.pop();

               if( nodeStack.empty() ) continue;

               Node& topNode = node[ nodeStack.top() ];
               topNode.mColorSet.insert(topColors.begin(),topColors.end());
               topNode.mChilds.erase(currentTop);
               continue;
           }
        }while(!nodeStack.empty());

        // output
        for( int i=1; i<=nNode; i++ )
        {
            cout << node[i].mColorSet.size();
            if( i != nNode )
            {
                cout << " ";
            }else{
                cout << endl;
            }
        }
    }
}