疯子.

给定一棵二叉树，找到它的最小深度。最小深度是从根节点到最近叶节点的最短路径上的节点数量

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, givens ="leetcode",dict =["leet", "code...

Given a string s and a dictionary of words dict, add spaces in s to construct a sentence where each word is a valid dictionary word. Return all such possible sentences. For example, givens ="catsa...

Given a binary tree, return the preorder traversal of its nodes' values.For example:Given binary tree{1,#,2,3}, 1 \ 2 / 3 return[1,2,3].Note: Recursive solution is trivi...

Given a binary tree, return the postorder traversal of its nodes' values.For example:Given binary tree{1,#,2,3}, 1 \ 2 / 3 return[3,2,1].Note: Recursive solution is triv...

Given a linked list, determine if it has a cycle in it.Follow up:Can you solve it without using extra space?思路：快慢指针/** * Definition for singly-linked list. * class ListNode { *     int val;...

Given a linked list, return the node where the cycle begins. If there is no cycle, returnnull.Follow up:Can you solve it without using extra space?思路：快慢指针/** * Definition for singly-linked lis...

Given a singly linked list L: L 0→L 1→…→L n-1→L n,reorder it to: L 0→L n →L 1→L n-1→L 2→L n-2→…You must do this in-place without altering the nodes' values.For example,Given{1,2,3,4}, reorder it...

Sort a linked list using insertion sort.使用插入排序对链表排序。/** * Definition for singly-linked list. * public class ListNode { *     int val; *     ListNode next; *     ListNode(int x) { *         v...

Given n points on a 2D plane, find the maximum number of points that lie on the same straight line.给定二维平面上的n个点，找出位于同一直线上的最大点数。原文：https://segmentfault.com/a/1190000005678407哈希表法复杂度O(N^2) 时间 O...

Sort a linked list in O(n log n) time using constant space complexity.使用固定的空间复杂度对链表进行排序，时间复杂度为O(n log n)思路：我们看到排序并且时间复杂度要求是O(n log n)，那么想到的排序方法是归并排序，只是使用的对象是链表，在归并排序的思想中，我们做的是每次查找中间下标，然后一分为二，递归下去，...

Evaluate the value of an arithmetic expression in Reverse Polish Notation.Valid operators are+,-,*,/. Each operand may be an integer or another expression.Some examples: ["2", "1", "+", "3", "...

Given a binary tree, find its minimum depth.The minimum depth is the number of nodes along the shortest path from the root node down to the nearest leaf node.给定一棵二叉树，找到它的最小深度。最小深度是沿着从根节点到最近叶节点的最短路径的...

在反向波动表示法中评估算术表达式的值。有效的运算符是+， - ，*，/。 每个操作数可能是一个整数或另一个表达式。

A linked list is given such that each node contains an additional random pointer which could point to any node in the list or null. Return a deep copy of the list./** * Definition for singly-link...