hackerrank 题目解析，php版本，算法不一定最优，但力求解释详细。
我会尽量多讲一些简单和普通难度的, 对新手友好一点, 同时, 也因为自己水平有限啊:)
- Alternating CharactersAlternating Characters
- Anagram Anagram
- Append and Delete Append and Delete
- Beautiful Binary String Beautiful Binary String
- Beautiful Pairs Beautiful Pairs
- Big Sorting Big Sorting
- Correctness and the Loop Invariant Correctness and the Loop Invariant
- Counting Sort 1 Counting Sort 1
- Counting Sort 2 Counting Sort 2
- Cut the sticks Cut the sticks
- Equalize the Array Equalize the Array
- Fair Rations Fair Rations
- Find Digits Find Digits
- Find the Median Find the Median
- Flatland Space Stations Flatland Space Stations
- Funny String Funny String
- Game of Thrones - I Game of Thrones - I
- Gemstones Gemstones
- Grid Challenge Grid Challenge
- Ice Cream Parlor Ice Cream Parlor
- Insertion Sort - Part 1 Insertion Sort - Part 1
- Insertion Sort - Part 2 Insertion Sort - Part 2
- Intro to Tutorial Challenges Intro to Tutorial Challenges
- Jim and the Orders Jim and the Orders
- Jumping on the CloudsJumping on the Clouds
- Jumping on the Clouds: Revisited Jumping on the Clouds: Revisited
- Largest Permutation Largest Permutation
- Library Fine Library Fine
- Lisa's Workbook Lisa's Workbook
- Lonely Integer Lonely Integer
- Luck Balance Luck Balance
- Making Anagrams Making Anagrams
- Mark and Toys Mark and Toys
- Maximizing XOR Maximizing XOR
- Maximum Perimeter Triangle Maximum Perimeter Triangle
- Misère Nim Misère Nim
- Missing Numbers Missing Numbers
- Nimble Game Nimble Game
- Palindrome Index Palindrome Index
- Pangrams Pangrams
- Permuting Two Arrays Permuting Two Arrays
- Poker Nim Poker Nim
- Priyanka and Toys Priyanka and Toys
- Quicksort 1 - Partition Quicksort 1 - Partition
- Repeated String Repeated String
- Running Time of Algorithms Running Time of Algorithms
- Separate the Numbers Separate the Numbers
- Sequence Equation Sequence Equation
- Sherlock and Array Sherlock and Array
- Sherlock and Squares Sherlock and Squares
- Sherlock and The Beast Sherlock and The Beast
- String Construction String Construction
- Super Reduced String Super Reduced String
- The Love-Letter Mystery The Love-Letter Mystery
- Two Characters Two Characters
- Two Strings Two Strings
- Viral Advertising Viral Advertising
- Weighted Uniform Strings Weighted Uniform Strings
- A stones game A stones game
- Beautiful Quadruples Beautiful Quadruples
- Bonetrousle Bonetrousle
- Breadth First Search: Shortest Reach Breadth First Search: Shortest Reach
- Bricks Game Bricks Game
- Candies Candies
- Candles Counting Candles Counting
- Chocolate in Box Chocolate in Box
- Clique Clique
- Cloudy Day Cloudy Day
- Coin on the Table Coin on the Table
- Crab Graphs Crab Graphs
- Equal Equal
- Even Tree Even Tree
- Extra Long Factorials Extra Long Factorials
- Extremum Permutations Extremum Permutations
- Flipping the Matrix Flipping the Matrix
- Gaming Array Gaming Array
- Gena Playing Hanoi Gena Playing Hanoi
- Goodland Electricity Goodland Electricity
- Greedy Florist Greedy Florist
- Grid Walking Grid Walking
- Gridland Metro Gridland Metro
- Hackerland Radio Transmitters Hackerland Radio Transmitters
- Interval Selection Interval Selection
- Jack goes to Rapture Jack goes to Rapture
- Jeanie's Route Jeanie's Route
- Journey to the Moon Journey to the Moon
- Kitty and Katty Kitty and Katty
- Knapsack Knapsack
- KnightL on a Chessboard KnightL on a Chessboard
- Kruskal (MST): Really Special Subtree Kruskal (MST): Really Special Subtree
- Lena Sort Lena Sort
- Max Min Max Min
- Minimum Loss Minimum Loss
- Minimum Penalty Path Minimum Penalty Path
- New Year Chaos New Year Chaos
- New Year Game New Year Game
- Pairs Pairs
- Permutation game Permutation game
- Play on benders Play on benders
- Play with words Play with words
- Prim's (MST) : Special Subtree Prim's (MST) : Special Subtree
- Red John is Back Red John is Back
- Red Knight's Shortest Path Red Knight's Shortest Path
- Roads and Libraries Roads and Libraries
- Sherlock and Cost Sherlock and Cost
- Snakes and Ladders: The Quickest Way Up Snakes and Ladders: The Quickest Way Up
- Substring DiffSubstring Diff
- Swap Permutation Swap Permutation
- Synchronous Shopping Synchronous Shopping
- The Coin Change Problem The Coin Change Problem
- The Indian Job The Indian Job
- The Longest Common Subsequence The Longest Common Subsequence
- The Story of a Tree The Story of a Tree
- Travel around the world Travel around the world
- Vertical Rooks Vertical Rooks
- Wet Shark and Two Subsequences Wet Shark and Two Subsequences
- Xor and Sum Xor and Sum
- Absolute Element Sums Absolute Element Sums
- Alex vs Fedor Alex vs Fedor
- Angry Children 2Angry Children 2
- Array Construction Array Construction
- Ashton and String Ashton and String
- Beautiful 3 Set Beautiful 3 Set
- Bike Racers Bike Racers
- ByteLandian Tours ByteLandian Tours
- Cards Permutation Cards Permutation
- Choosing White Balls Choosing White Balls
- Count Strings Count Strings
- Cutting Boards Cutting Boards
- Decibinary Numbers Decibinary Numbers
- Demanding Money Demanding Money
- Determining DNA Health Determining DNA Health
- Dijkstra: Shortest Reach 2 Dijkstra: Shortest Reach 2
- Distant Pairs Distant Pairs
- Favorite sequence Favorite sequence
- Find Strings Find Strings
- Frog in Maze Frog in Maze
- HackerX HackerX
- Inverse RMQ Inverse RMQ
- Jim and his LAN Party Jim and his LAN Party
- Jogging Cats Jogging Cats
- Lovely Triplets Lovely Triplets
- Making Candies Making Candies
- Minimum MST Graph Minimum MST Graph
- Quadrant Queries Quadrant Queries
- Real Estate Broker Real Estate Broker
- Recording Episodes Recording Episodes
- Repair Roads Repair Roads
- Repetitive K-Sums Repetitive K-Sums
- Savita And Friends Savita And Friends
- Sherlock's Array Merging Algorithm Sherlock's Array Merging Algorithm
- Similar Pair Similar Pair
- String Function Calculation String Function Calculation
- String Reduction String Reduction
- Subset Component Subset Component
- Super Functional Strings Super Functional Strings
- Tara's Beautiful Permutations Tara's Beautiful Permutations
- Task Scheduling Task Scheduling
- The Longest Increasing Subsequence The Longest Increasing Subsequence
- The Value of Friendship The Value of Friendship
- Ticket Ticket
- Toll Cost Digits Toll Cost Digits
- Training the army Training the army
- Tree Flow Tree Flow
- Tree Pruning Tree Pruning
- Tripartite Matching Tripartite Matching
- Yet Another KMP Problem Yet Another KMP Problem