Solutions to 21DC problems

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#	Title	Code	Difficulty
D1P1	Number of Steps to Reduce a Number to Zero	Java Python	Easy
D1P2	Non-decreasing Array	Java Python	Easy
D1P3	Hamming Distance	C++ Python	Easy
D2P1	Third Maximum Number	Java Python	Easy
D2P2	Island Perimeter	C++ Python	Easy
D2P3	Kids With the Greatest Number of Candies	Java Python	Easy
D3P1	Consecutive Characters	Java Python	Easy
D3P2	Deck of Cards	Java Python	Easy
D3P3	Unique no. of occurences	Java Python	Easy
D4P1	Min Cost Climbing Stairs	C++ Python	Easy
D4P2	Split a String in Balanced Strings	Java Python	Easy
D4P3	Best time to buy and sell stocks	Java Python	Easy
D5P1	House robber	Java Python	Easy
D5P2	Backspace String Compare	C++ Python	Easy
D5P3	Plus One	Java Python	Easy
D6P1	Range sum of BST	Java Python	Easy
D6P2	Linked List Cycle	C++ (2 Pointers) C++ (Set) Python	Easy
D6P3	Build an Array With Stack Operations	Java Python	Easy
D7P1	Valid Parentheses	Java Python	Easy
D7P2	Assign Cookies	C++ Python	Easy
D7P3	Top K Frequent Words	Java Python	Easy
D8P1	Number of Matching Subsequences	Java	Medium
D8P2	Unique Paths	C++	Medium
D8P3	Longest Univalue Path	Java	Easy
D9P1	Simplified Fractions	Java	Medium
D9P2	Product of Array Except Self	C++	Medium
D9P3	remove K digits	Java	Medium
D10P1	Maximum Area of a Piece of Cake	C++	Medium
D10P2	Intersection of Two Arrays	Java	Easy
D10P3	Partition Equal Subset Sum	Java	Medium
D11P1	Longest Palindrome	C++ Java	Medium
D11P2	Buddy strings	C++ Java	Easy
D11P3	Design browser history	C++ Java	Medium
D12P1	The k Strongest Values in an Array	C++ Java	Medium
D12P2	Arithematic Slices	C++ Java	Medium
D12P3	Decode String	C++ Java	Medium
D13P1	pseudo palindromic paths	C++ Java	Medium
D13P2	Integer Break	C++ Java	Medium
D13P3	Bulb Switcher III	C++ Java	Medium
D14P1	Reorder Routes to Make All Paths Lead to the City Zero	C++ Java	Medium
D14P2	Binary Tree Pruning	C++ Java	Medium
D14P3	get Maximum Gold	C++ Java	Medium
D15P1	Insert Delete GetRandom O(1)	C++ Java	Medium
D15P2	Max Sum Div Three	C++ Java	Medium
D15P3	Word Subsets	C++ Java	Medium
D16P1	Regular Expression Matching	C++ Java	Medium
D16P2	Koko Eating Bananas	C++ Java	Medium
D16P3	Number of Operations to Make Network Connected	C++ Java	Medium
D17P1	Vowel spellchecker	Java	Medium
D17P2	Rotting Oranges	C++ Java	Medium
D17P3	Predict the winner	Java	Medium
D18P1	Longest happy string	C++ Java	Medium
D18P2	Delete and earn	C++ Java	Medium
D18P3	Find Eventual Safe States	C++ Java	Medium
D19P1	Min Score Triangulation	Java	Medium
D19P2	Task Scheduler	C++ Java	Medium
D19P3	Push Dominoes	C++ Java	Medium
D20P1	Minimum ASCII Delete Sum for Two Strings	C++ Java	Medium
D20P2	Distinct Subsequences	C++ Java	Hard
D20P3	Filling Bookcase Shelves	C++ Java	Medium
D21P1	Path Sum	C++ Java	Medium
D21P2	Permutation Sequence	C++ Java	Medium
D21P3	Split Array Same Average	C++	Hard