首页 > 其他 > 详细

[leetcode] 98 Validate Binary Search Tree

时间:2015-01-14 22:50:56      阅读:365      评论:0      收藏:0      [点我收藏+]

问题描述:

Given a binary tree, determine if it is a valid binary search tree (BST).

Assume a BST is defined as follows:

  • The left subtree of a node contains only nodes with keys less than the node‘s key.
  • The right subtree of a node contains only nodes with keys greater than the node‘s key.
  • Both the left and right subtrees must also be binary search trees.

代码:

bool isValidBST(TreeNode *root) {  //C++
        if(root == NULL||(root->left==NULL &&root->right==NULL))
            return true;
        
        int pre;
        bool isFirst = true;
        stack<TreeNode*> myStack;
        TreeNode* p = root;
        while(p!=NULL || !myStack.empty())
        {
            while(p!=NULL){
                myStack.push(p);
                p = p->left;
            }
            p = myStack.top();
            if(isFirst){
                isFirst = false;
                pre = p->val;   
            }
            else{
                if(p->val <=pre)
                    return false;
                pre = p->val;
            }
            myStack.pop();
            p = p->right;
        }
                
        return true;
    }


[leetcode] 98 Validate Binary Search Tree

原文:http://blog.csdn.net/chenlei0630/article/details/42718747

(0)
(0)
   
举报
评论 一句话评论(0
关于我们 - 联系我们 - 留言反馈 - 联系我们:wmxa8@hotmail.com
© 2014 bubuko.com 版权所有
打开技术之扣,分享程序人生!