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.Th...
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其他好文 时间：
2014-07-13 16:53:01
阅读次数：
189
Given a linked list, determine if it has a cycle in it.
Follow up:
Can you solve it without using extra space?
/**
* Definition for singly-linked list.
* class ListNode {
* int val;
* ...
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其他好文 时间：
2014-07-13 16:32:04
阅读次数：
152
Given a string containing just the characters '(', ')', '{', '}', '[' and ']',
determine if the input string is valid.
The brackets must close in the correct order, "()" and "()[]{}" are
all va...
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其他好文 时间：
2014-07-13 16:11:26
阅读次数：
144
Given a binary tree and a sum, determine if the tree has a root-to-leaf path such that adding up all the values along the path equals the given sum.
For example:
Given the below binary tree and sum
...
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其他好文 时间：
2014-07-13 13:58:01
阅读次数：
184
Given a string, determine if it is a palindrome, considering only alphanumeric characters and ignoring cases.
For example,
"A man, a plan, a canal: Panama" is a palindrome.
"race a car" is not a ...
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其他好文 时间：
2014-07-12 20:10:54
阅读次数：
165
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.Th...
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其他好文 时间：
2014-07-12 17:26:31
阅读次数：
256
Given a string s and a dictionary of words dict, determine if s can be segmented into a space-separated sequence of one or more dictionary words.
For example, given
s = "leetcode",
dict = ["leet"...
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其他好文 时间：
2014-07-10 20:57:26
阅读次数：
215
An IP address is 32-bit long. IP addresses are classified into A, B, C, D, and E classes, as shown in the figure below.
Please determine the class of an input IP address and obtain the corresponding IP address information according to the input 32-bit IP ...
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其他好文 时间：
2014-07-09 12:43:54
阅读次数：
232
题目
Given a binary tree and a sum, determine if the tree has a root-to-leaf path such that adding up all the values along the path equals the given sum.
For example:
Given the below binary tree ...
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其他好文 时间：
2014-07-09 10:32:42
阅读次数：
151
题目
Given a linked list, determine if it has a cycle in it.
Follow up:
Can you solve it without using extra space?
解答
首先要注意空链表不成环;不能开额外的空间，即空间复杂度是o(1),可采用“快慢指针”查检查链表是否含有环，如果在快的指针能够追上慢的指针，则有环，否...
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其他好文 时间：
2014-07-08 19:17:47
阅读次数：
160
