104. Maximum Depth of Binary Tree

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Given a binary tree, find its maximum depth.

The maximum depth is the number of nodes along the longest path from the root node down to the farthest leaf node.

同Minimum Depth of Binary Tree求解类似。 http://qiaopeng688.blog.51cto.com/3572484/1835237 

代码如下：

/**
 * Definition for a binary tree node.
 * struct TreeNode {
 *     int val;
 *     TreeNode *left;
 *     TreeNode *right;
 *     TreeNode(int x) : val(x), left(NULL), right(NULL) {}
 * };
 */
class Solution {
public:
    int maxDepth(TreeNode* root) {
        int iMaxDepth = 0;
        vector depths;
        stack s;
        
        TreeNode *p,*q;
        q = NULL;
        p = root;
        if(!root)
            return 0;
        while(p != NULL || s.size() > 0)
        {
            while( p != NULL)
            {
                s.push(p);
                p = p->left;
            }
            if(s.size() > 0)
            {
                p = s.top();
                 
                if( NULL == p->left && NULL == p->right)
                {
                    if(iMaxDepth < s.size())
                        iMaxDepth = s.size();
                }
                 
                if( (NULL == p->right || p->right == q) )
                {
                    q = p;
                    s.pop();
                    p = NULL;
                }
                else
                    p = p->right;
            }
        }
        return iMaxDepth;
    }
};