interview fb2

2014.7.8fb

#include <iostream>
using namespace std;

struct TreeNode{
    int val;
    TreeNode *left;
    TreeNode *right;
    TreeNode(int val)
    {
        left = NULL;
        right = NULL;
    }
};

/*

Input : binary tree

      A
     / \
    B   C
   / \   \
  D   E   G
       \   \
        F   H

Output : 
A
BC
DEG
FH
*/
vector<vector<int> > transform(TreeNode *root)
{
    vector<vector<int> ans;
    if(root == NULL)
        return ans;
    
    vector<int> ans_piece;
    queue<TreeNode *> last_time;
    
    queue.push_back(root);
    TreeNode *temp;
    
    vector<int> num_each;
    num_each.push_back(1);
    num_each.push_back(0);
    int level = 0;
    while(queue.empty() == false)
    {
        num_each[level]--;
        
        temp = queue.get_first_one();
        queue.pop();
        if(temp)
            ans_piece.push_back(temp->val);
        if(temp->left)
        {
            queue.push_back(temp->left);
            num_each[level+1]++;
        }
        if(temp->right)
        {
            queue.push_back(temp->right);
            num_each[level+1]++;
        }
            
        if(num_each[level] == 0)
        {
            ans.push_back(ans_piece);
            level++;
            ans_piece.clear();
            num_each.push_back(0);
        }
    }
    return ans;
}