归档 2015年7月

[LeetCode]Lowest Common Ancestor of a Binary Tree

题目描述:

Given a binary tree, find the lowest common ancestor (LCA) of two given nodes in the tree.

According to the definition of LCA on Wikipedia: “The lowest common ancestor is defined between two nodes v and w as the ...

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[LeetCode]Lowest Common Ancestor of a Binary Search Tree

题目描述:

Given a binary search tree (BST), find the lowest common ancestor (LCA) of two given nodes in the BST.

According to the definition of LCA on Wikipedia: “The lowest common ancestor is defined between two nodes v and w ...

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[LeetCode]Linked List Cycle II

题目描述:

Given a linked list, return the node where the cycle begins. If there is no cycle, return null.

Follow up:
Can you solve it without using extra space?

题目大意:

给定一个链表,返回循环的起始节点。如果没有环,则返回空。

进一步思考:

你可以在不使用额外空间的条件下完成题目吗?

解题思路:

参考LeetCode Discuss(https ...

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[LeetCode]Palindrome Linked List

题目描述:

Given a singly linked list, determine if it is a palindrome.

Follow up:
Could you do it in O(n) time and O(1) space?

题目大意:

给定一个单链表,判断它是否是回文。

进一步思考:

你可以在O(n)时间复杂度和O(1)空间复杂度完成吗?

解题思路:

1). 使用快慢指针寻找链表中点

2). 将链表的后半部分就地逆置 ...

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