There are N children standing in a line. Each child is assigned a rating value. You are giving candies to these children subjected to the following requirements: 1. Each child must have at least one candy. 2. Children with a higher rating get more candies than their neighbors. What is the minimum candies you must … Read more
This post shows how to migrate a php website from 1and1 shared hosting to Amazon AWS. I mainly cover the Linux command lines and various configurations since they are often the difficult part. I will cover the steps for creating instances of AWS because they can be done by following the guide provided by Amazon … Read more
Given an unsorted array, find the maximum difference between the successive elements in its sorted form. Try to solve it in linear time/space. Return 0 if the array contains less than 2 elements. You may assume all elements in the array are non-negative integers and fit in the 32-bit signed integer range. Analysis We can … Read more
Problem Given two integers representing the numerator and denominator of a fraction, return the fraction in string format. If the fractional part is repeating, enclose the repeating part in parentheses. For example, Given numerator = 1, denominator = 2, return “0.5”. Given numerator = 2, denominator = 1, return “2”. Given numerator = 2, denominator … Read more
Problem Given a positive integer, return its corresponding column title as appear in an Excel sheet. For example: 1 -> A 2 -> B 3 -> C … 26 -> Z 27 -> AA 28 -> AB Java Solution This problem is the reverse version of Excel Sheet Column Number. The key is n–. The … Read more
Problem Given a column title as appear in an Excel sheet, return its corresponding column number. For example: A -> 1 B -> 2 C -> 3 … Z -> 26 AA -> 27 AB -> 28 … AAA -> 703 Java Solution This problem is related to Excel Sheet Column Title. public int titleToNumber(String … Read more
There are N gas stations along a circular route, where the amount of gas at station i is gas[i]. You have a car with an unlimited gas tank and it costs cost[i] of gas to travel from station i to its next station (i+1). You begin the journey with an empty tank at one of … Read more
Problem Given an array of integers, every element appears three times except for one. Find that single one. Java Solution This problem is similar to Single Number. public int singleNumber(int[] A) { int ones = 0, twos = 0, threes = 0; for (int i = 0; i < A.length; i++) { twos |= ones … Read more
Problem Compare two version numbers version1 and version2. If version1 > version2 return 1, if version1 < version2 return -1, otherwise return 0. You may assume that the version strings are non-empty and contain only digits and the . character. The . character does not represent a decimal point and is used to separate number ... Read more
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, given s = “catsanddog”, dict = [“cat”, “cats”, “and”, “sand”, “dog”], the solution is [“cats and dog”, “cat sand dog”]. Java Solution … Read more
Find the contiguous subarray within an array (containing at least one number) which has the largest product. For example, given the array [2,3,-2,4], the contiguous subarray [2,3] has the largest product = 6. Java Solution – Dynamic Programming This is similar to maximum subarray. Instead of sum, the sign of number affect the product value. … Read more
Follow up for “Find Minimum in Rotated Sorted Array”: What if duplicates are allowed? Would this affect the run-time complexity? How and why? Java Solution 1 – Recursion This is a follow-up problem of finding minimum element in rotated sorted array without duplicate elements. We only need to add one more condition, which checks if … Read more
Given two integers n and k, return all possible combinations of k numbers out of 1 … n. For example, if n = 4 and k = 2, a solution is: [ [2,4], [3,4], [2,3], [1,2], [1,3], [1,4], ] Java Solution public ArrayList<ArrayList<Integer>> combine(int n, int k) { ArrayList<ArrayList<Integer>> result = new ArrayList<ArrayList<Integer>>(); if … Read more
