Leetcode121 Best Time to Buy and Sell Stock

题目描述

Example 1:

1
2
3
4

Input: [7,1,5,3,6,4]
Output: 5
Explanation: Buy on day 2 (price = 1) and sell on day 5 (price = 6), profit = 6-1 = 5.
             Not 7-1 = 6, as selling price needs to be larger than buying price.

Leetcode21.Merge Two Sorted Lists

题目描述

1
2
3
4
5

Merge two sorted linked lists and return it as a new list. 
The new list should be made by splicing together the nodes of the first two lists.
Example:
Input: 1->2->4, 1->3->4
Output: 1->1->2->3->4->4

Leetcode138. Copy List with Random Pointer

题目描述

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.

The Linked List is represented in the input/output as a list of n nodes. Each node is represented as a pair of [val, random_index] where:

• val: an integer representing Node.val

• random_index: the index of the node (range from 0 to n-1) where random pointer points to, or null if it does not point to any node.

Leetcode139 WordBreak

题目描述

Given a non-empty string s and a dictionary wordDict containing a list of non-empty words, determine if s can be segmented into a space-separated sequence of one or more dictionary words.

Note:

• The same word in the dictionary may be reused multiple times in the segmentation.
• You may assume the dictionary does not contain duplicate words.

Leetcode200 Number of Islands

题目描述

Given a 2d grid map of '1's (land) and '0's (water), count the number of islands. An island is surrounded by water and is formed by connecting adjacent lands horizontally or vertically. You may assume all four edges of the grid are all surrounded by water.

Leetcode210 Course ScheduleII

题目描述

There are a total of n courses you have to take, labeled from 0 to n-1.

Some courses may have prerequisites, for example to take course 0 you have to first take course 1, which is expressed as a pair: [0,1]

Given the total number of courses and a list of prerequisite pairs, return the ordering of courses you should take to finish all courses.

There may be multiple correct orders, you just need to return one of them. If it is impossible to finish all courses, return an empty array.

Leetcode273 Integer to English Words

题目描述

Convert a non-negative integer to its English words representation. Given input is guaranteed to be less than 2的31 - 1.

Leetcode295 Find Median from Data Stream

题目描述

Median is the middle value in an ordered integer list. If the size of the list is even, there is no middle value. So the median is the mean of the two middle value.

Leetcode240 Search a 2D Matrix II

题目描述

Write an efficient algorithm that searches for a value in an m x n matrix. This matrix has the following properties:

• Integers in each row are sorted in ascending from left to right.
• Integers in each column are sorted in ascending from top to bottom.

Leetcode347 Top K Frequent Elements

题目描述

Given a non-empty array of integers, return the k\ most frequent elements.

Example 1:

1
2

Input: nums = [1,1,1,2,2,3], k = 2
Output: [1,2]