Ray1988’s gists

Ray1988 / BestTimeToBuyandSellStockII.java

Created July 10, 2014 05:53

	/*
	Say you have an array for which the ith element is the price of a given stock on day i.
	Design an algorithm to find the maximum profit. You may complete as many transactions
	as you like (ie, buy one and sell one share of the stock multiple times). However,
	you may not engage in multiple transactions at the same time
	(ie, you must sell the stock before you buy again).
	*/


	public class Solution {

Ray1988 / GenerateParentheses.java

Created July 1, 2014 02:26

Java


	/*
	Given n pairs of parentheses, write a function to generate all combinations of well-formed parentheses.

	For example, given n = 3, a solution set is:

	"((()))", "(()())", "(())()", "()(())", "()()()"
	*/

	public class Solution {

Ray1988 / climbingStars.java

Created June 28, 2014 06:31

Java

	/*
	You are climbing a stair case. It takes n steps to reach to the top.

	Each time you can either climb 1 or 2 steps. In how many distinct ways can you climb to the top?
	*/

	//DP Solution


	public class Solution {

Ray1988 / Best TimetoBuyandSellStock.java

Created June 27, 2014 04:51

Java

	/*
	Say you have an array for which the ith element is the price of a given stock on day i.

	If you were only permitted to complete at most one transaction (ie, buy one and sell one share of the stock), design an algorithm to find the maximum profit.
	*/

	public class Solution {
	public int maxProfit(int[] prices) {
	if (prices==null \|\| prices.length==0){
	return 0;

Ray1988 / UniquePath.java

Created June 25, 2014 06:12

Java

	/*
	A 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 are there?



	*/

Ray1988 / BinaryTreePostorderTrave.java

Last active August 29, 2015 14:02

	/*
	Given a binary tree, return the postorder traversal of its nodes' values.

	For example:
	Given binary tree {1,#,2,3},
	1
	\
	2
	/
	3

Ray1988 / MinimumPathSum.java

Created June 16, 2014 05:39

Java

	// Failed on time limitation, faster solution below
	public class Solution {
	public int minPathSum(int[][] grid) {
	if (grid==null \|\| grid.length==0){
	return 0;
	}

	int[] minPath={Integer.MAX_VALUE};
	int currentX=0;
	int currentY=0;

Ray1988 / SearchA2DMatrix.java

Created June 16, 2014 01:41

java

	/*
	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 from left to right.
	The first integer of each row is greater than the last integer of the previous row.
	For example,

	Consider the following matrix:

	[

Ray1988 / SearchA2DMattix.py

Created June 15, 2014 18:08

Python

	"""
	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 from left to right.
	The first integer of each row is greater than the last integer of the previous row.
	For example,

	Consider the following matrix:

	[

Ray1988 / ContainerWithMostWater.py

Created June 12, 2014 06:16

python

	"""
	Given n non-negative integers a1, a2, ..., an, where each represents a point at coordinate (i, ai). n vertical lines are drawn such that the two endpoints of line i is at (i, ai) and (i, 0). Find two lines, which together with x-axis forms a container, such that the container contains the most water.

	Note: You may not slant the container.
	"""


	class Solution:
	# @return an integer
	def maxArea(self, height):

Xinghua Li Ray1988