Given a binary tree containing digits from 0-9 only, each root-to-leaf path could represent a number.

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.

Given an unsorted array of integers, find the length of longest increasing subsequence.

Given a matrix consists of 0 and 1, find the distance of the nearest 0 for each cell.

There are N students in a class. Some of them are friends, while some are not. Their friendship is transitive in nature. For example, if A is a direct friend of B, and B is a direct friend of C, then A is an indirect friend of C. And we defined a friend circle is a group of students who are direc...

Given a non-empty 2D array grid of 0's and 1's, an island is a group of 1's (representing land) connected 4-directionally (horizontal or vertical.) You may assume all four edges of the grid are surrounded by water.

The maximum depth is the number of nodes along the longest path from the root node down to the farthest leaf node.

Given an array where elements are sorted in ascending order, convert it to a height balanced BST.

Given a binary tree, return the inorder traversal of its nodes' values.

Now consider if some obstacles are added to the grids. How many unique paths would there be?

robot is located at the top-left corner of a m x n grid (marked 'Start' in the diagram below).The robot can only move either down or right at any point in time. The robot is trying to reach the bottom-right corner of the grid (marked 'Finish' in the diagram below).How many possible unique paths a...

Given a triangle, find the minimum path sum from top to bottom. Each step you may move to adjacent numbers on the row below.

You are a professional robber planning to rob houses along a street. Each house has a certain amount of money stashed, the only constraint stopping you from robbing each of them is that adjacent houses have security system connected and it will automatically contact the police if two adjacent hou...

 是一种在数学、管理科学、计算机科学、经济学和生物信息学中使用的，通过把原问题分解为相对简单的子问题的方式求解复杂问题的方法。       动态规划常常适用于有重叠子问题[1]和最优子结构性质的问题，动态规划方法所耗时间往往远少于朴素解法。       动态规划背后的基本思想非常简单。大致上，若要解一个给定问题，...