binary-tree-level-order-traversal-ii

gistfile1.cpp

https://oj.leetcode.com/problems/binary-tree-level-order-traversal-ii/

/**
 * Definition for binary tree
 * struct TreeNode {
 *     int val;
 *     TreeNode *left;
 *     TreeNode *right;
 *     TreeNode(int x) : val(x), left(NULL), right(NULL) {}
 * };
 */
 
class Solution {
public:
    vector<vector<int> > levelOrderBottom(TreeNode *root) {
        vector<vector<int>> res;
        
        if(root == NULL) {
            return res;
        }
        
        queue<TreeNode*> queue;
        queue.push(root);
        while(!queue.empty()) {
            
            int width = queue.size();
            vector<int> breadth;
            
            for(int i=0; i<width ; ++i) {
                TreeNode* temp = queue.front();
                queue.pop();
                breadth.push_back(temp->val);
                
                if(temp->left) {
                    queue.push(temp->left);
                }
            
                if(temp->right) {
                    queue.push(temp->right);
                }    
            }
            
            res.push_back(breadth);
        }
        
        std::reverse(res.begin(), res.end());
        
        return res;
    }
};