Updated README

Author: das-jishu

README.md

@@ -102,6 +102,79 @@ The questions are not ordered so you might need to search for a bit.
 | :star: | Reverse Words In String | :blue_square: | [reverse-words-in-string.py](https://github.com/das-jishu/algoexpert-data-structures-algorithms/blob/master/Medium/reverse-words-in-string.py) |
 | :star: | Minimum Characters For Words | :blue_square: | [minimum-characters-for-words.py](https://github.com/das-jishu/algoexpert-data-structures-algorithms/blob/master/Medium/minimum-characters-for-words.py) |
 | :star: | Suffix Trie Construction | :blue_square: | [suffix-trie-construction.py](https://github.com/das-jishu/algoexpert-data-structures-algorithms/blob/master/Medium/suffix-trie-construction.py) |
+| :star: | Four Number Sum | :red_sqaure: | [four-number-sum.py](https://github.com/das-jishu/algoexpert-data-structures-algorithms/blob/master/Hard/four-number-sum.py) |
+| :star: | Subarray Sort | :red_sqaure: | [subarray-sort.py](https://github.com/das-jishu/algoexpert-data-structures-algorithms/blob/master/Hard/subarray-sort.py) |
+| :star: | Largest Range | :red_sqaure: | [largest-range.py](https://github.com/das-jishu/algoexpert-data-structures-algorithms/blob/master/Hard/largest-range.py) |
+| :star: | Min Rewards | :red_sqaure: | [min-rewards.py](https://github.com/das-jishu/algoexpert-data-structures-algorithms/blob/master/Hard/min-rewards.py) |
+| :star: | Zigzag Traverse | :red_sqaure: | [zigzag-traverse.py](https://github.com/das-jishu/algoexpert-data-structures-algorithms/blob/master/Hard/zigzag-traverse.py) |
+| :star: | Same bsts | :red_sqaure: | [same-bsts.py](https://github.com/das-jishu/algoexpert-data-structures-algorithms/blob/master/Hard/same-bsts.py) |
+| :star: | Validate Three Nodes | :red_sqaure: | [validate-three-nodes.py](https://github.com/das-jishu/algoexpert-data-structures-algorithms/blob/master/Hard/validate-three-nodes.py) |   
+| :star: | Max Path Sum In Binary Tree | :red_sqaure: | [max-path-sum-in-binary-tree.py](https://github.com/das-jishu/algoexpert-data-structures-algorithms/blob/master/Hard/max-path-sum-in-binary-tree.py) |
+| :star: | Find Nodes Distance K | :red_sqaure: | [find-nodes-distance-k.py](https://github.com/das-jishu/algoexpert-data-structures-algorithms/blob/master/Hard/find-nodes-distance-k.py) || :star: | Max Sum Increasing Subsequence | :red_sqaure: | [max-sum-increasing-subsequence.py](https://github.com/das-jishu/algoexpert-data-structures-algorithms/blob/master/Hard/max-sum-increasing-subsequence.py) |
+| :star: | Longest Common Subsequence | :red_sqaure: | [longest-common-subsequence.py](https://github.com/das-jishu/algoexpert-data-structures-algorithms/blob/master/Hard/longest-common-subsequence.py) |
+| :star: | Min Number of Jumps | :red_sqaure: | [min-number-of-jumps.py](https://github.com/das-jishu/algoexpert-data-structures-algorithms/blob/master/Hard/min-number-of-jumps.py) |      
+| :star: | Water Area | :red_sqaure: | [water-area.py](https://github.com/das-jishu/algoexpert-data-structures-algorithms/blob/master/Hard/water-area.py) |
+| :star: | Knapsack Problem | :red_sqaure: | [knapsack-problem.py](https://github.com/das-jishu/algoexpert-data-structures-algorithms/blob/master/Hard/knapsack-problem.py) |
+| :star: | Disk Stacking | :red_sqaure: | [disk-stacking.py](https://github.com/das-jishu/algoexpert-data-structures-algorithms/blob/master/Hard/disk-stacking.py) |
+| :star: | Numbers in Pi | :red_sqaure: | [numbers-in-pi.py](https://github.com/das-jishu/algoexpert-data-structures-algorithms/blob/master/Hard/numbers-in-pi.py) |
+| :star: | Maximum Sum Submatrix | :red_sqaure: | [maximum-sum-submatrix.py](https://github.com/das-jishu/algoexpert-data-structures-algorithms/blob/master/Hard/maximum-sum-submatrix.py) || :star: | Maximize Expression | :red_sqaure: | [maximize-expression.py](https://github.com/das-jishu/algoexpert-data-structures-algorithms/blob/master/Hard/maximize-expression.py) |      
+| :star: | Dijkstra Algorithm | :red_sqaure: | [dijkstra-algorithm.py](https://github.com/das-jishu/algoexpert-data-structures-algorithms/blob/master/Hard/dijkstra-algorithm.py) |
+| :star: | Topological Sort | :red_sqaure: | [topological-sort.py](https://github.com/das-jishu/algoexpert-data-structures-algorithms/blob/master/Hard/topological-sort.py) |
+| :star: | Boggle Board | :red_sqaure: | [boggle-board.py](https://github.com/das-jishu/algoexpert-data-structures-algorithms/blob/master/Hard/boggle-board.py) |
+| :star: | Continuous Median | :red_sqaure: | [continuous-median.py](https://github.com/das-jishu/algoexpert-data-structures-algorithms/blob/master/Hard/continuous-median.py) |
+| :star: | Sort K Sorted Array | :red_sqaure: | [sort-k-sorted-array.py](https://github.com/das-jishu/algoexpert-data-structures-algorithms/blob/master/Hard/sort-k-sorted-array.py) |      
+| :star: | Laptop Rentals | :red_sqaure: | [laptop-rentals.py](https://github.com/das-jishu/algoexpert-data-structures-algorithms/blob/master/Hard/laptop-rentals.py) |
+| :star: | Find Loop | :red_sqaure: | [find-loop.py](https://github.com/das-jishu/algoexpert-data-structures-algorithms/blob/master/Hard/find-loop.py) |
+| :star: | Reverse Linked List | :red_sqaure: | [reverse-linked-list.py](https://github.com/das-jishu/algoexpert-data-structures-algorithms/blob/master/Hard/reverse-linked-list.py) |      
+| :star: | Merge Linked Lists | :red_sqaure: | [merge-linked-lists.py](https://github.com/das-jishu/algoexpert-data-structures-algorithms/blob/master/Hard/merge-linked-lists.py) |
+| :star: | Shift Linked Lists | :red_sqaure: | [shift-linked-lists.py](https://github.com/das-jishu/algoexpert-data-structures-algorithms/blob/master/Hard/shift-linked-lists.py) |
+| :star: | Lowest Common Manager | :red_sqaure: | [lowest-common-manager.py](https://github.com/das-jishu/algoexpert-data-structures-algorithms/blob/master/Hard/lowest-common-manager.py) || :star: | Interweaving Strings | :red_sqaure: | [interweaving-strings.py](https://github.com/das-jishu/algoexpert-data-structures-algorithms/blob/master/Hard/interweaving-strings.py) |   
+| :star: | Solve Sudoku | :red_sqaure: | [solve-sudoku.py](https://github.com/das-jishu/algoexpert-data-structures-algorithms/blob/master/Hard/solve-sudoku.py) |
+| :star: | Generate Div Tags | :red_sqaure: | [generate-div-tags.py](https://github.com/das-jishu/algoexpert-data-structures-algorithms/blob/master/Hard/generate-div-tags.py) |
+| :star: | Ambiguous Measurements | :red_sqaure: | [ambiguous-measurements.py](https://github.com/das-jishu/algoexpert-data-structures-algorithms/blob/master/Hard/ambiguous-measurements.py) |
+| :star: | Shifted Binry Search | :red_sqaure: | [shifted-binry-search.py](https://github.com/das-jishu/algoexpert-data-structures-algorithms/blob/master/Hard/shifted-binry-search.py) |   
+| :star: | Search For Range | :red_sqaure: | [search-for-range.py](https://github.com/das-jishu/algoexpert-data-structures-algorithms/blob/master/Hard/search-for-range.py) |
+| :star: | Quickselect | :red_sqaure: | [quickselect.py](https://github.com/das-jishu/algoexpert-data-structures-algorithms/blob/master/Hard/quickselect.py) |
+| :star: | Index Equals Value | :red_sqaure: | [index-equals-value.py](https://github.com/das-jishu/algoexpert-data-structures-algorithms/blob/master/Hard/index-equals-value.py) |
+| :star: | Quick Sort | :red_sqaure: | [quick-sort.py](https://github.com/das-jishu/algoexpert-data-structures-algorithms/blob/master/Hard/quick-sort.py) |
+| :star: | Heap Sort | :red_sqaure: | [heap-sort.py](https://github.com/das-jishu/algoexpert-data-structures-algorithms/blob/master/Hard/heap-sort.py) |
+| :star: | Radix Sort | :red_sqaure: | [radix-sort.py](https://github.com/das-jishu/algoexpert-data-structures-algorithms/blob/master/Hard/radix-sort.py) |
+| :star: | Shorten Path | :red_sqaure: | [shorten-path.py](https://github.com/das-jishu/algoexpert-data-structures-algorithms/blob/master/Hard/shorten-path.py) |
+| :star: | Largest Rectangle Under Skyline | :red_sqaure: | [largest-rectangle-under-skyline.py](https://github.com/das-jishu/algoexpert-data-structures-algorithms/blob/master/Hard/largest-rectangle-under-skyline.py) |
+| :star: | Longest Substring Without Duplication | :red_sqaure: | [longest-substring-without-duplication.py](https://github.com/das-jishu/algoexpert-data-structures-algorithms/blob/master/Hard/longest-substring-without-duplication.py) |
+| :star: | Underscorify Substring | :red_sqaure: | [underscorify-substring.py](https://github.com/das-jishu/algoexpert-data-structures-algorithms/blob/master/Hard/underscorify-substring.py) |
+| :star: | Pattern Matcher | :red_sqaure: | [pattern-matcher.py](https://github.com/das-jishu/algoexpert-data-structures-algorithms/blob/master/Hard/pattern-matcher.py) |
+| :star: | Multi String Search | :red_sqaure: | [multi-string-search.py](https://github.com/das-jishu/algoexpert-data-structures-algorithms/blob/master/Hard/multi-string-search.py) |      
+| :star: | Apartment Hunting | :black_large_square: | [apartment-hunting.py](https://github.com/das-jishu/algoexpert-data-structures-algorithms/blob/master/Very%20Hard/apartment-hunting.py) |
+| :star: | Calendar Matching | :black_large_square: | [calendar-matching.py](https://github.com/das-jishu/algoexpert-data-structures-algorithms/blob/master/Very%20Hard/calendar-matching.py) |
+| :star: | Waterfall Streams | :black_large_square: | [waterfall-streams.py](https://github.com/das-jishu/algoexpert-data-structures-algorithms/blob/master/Very%20Hard/waterfall-streams.py) |
+| :star: | Minimum Area Rectangle | :black_large_square: | [minimum-area-rectangle.py](https://github.com/das-jishu/algoexpert-data-structures-algorithms/blob/master/Very%20Hard/minimum-area-rectangle.py) |
+| :star: | Line Through Points | :black_large_square: | [line-through-points.py](https://github.com/das-jishu/algoexpert-data-structures-algorithms/blob/master/Very%20Hard/line-through-points.py) |
+| :star: | Right Smaller Than | :black_large_square: | [right-smaller-than.py](https://github.com/das-jishu/algoexpert-data-structures-algorithms/blob/master/Very%20Hard/right-smaller-than.py) |
+| :star: | Iterative Inorder Traversal | :black_large_square: | [iterative-inorder-traversal.py](https://github.com/das-jishu/algoexpert-data-structures-algorithms/blob/master/Very%20Hard/iterative-inorder-traversal.py) |
+| :star: | Flatten Binary Tree | :black_large_square: | [flatten-binary-tree.py](https://github.com/das-jishu/algoexpert-data-structures-algorithms/blob/master/Very%20Hard/flatten-binary-tree.py) |
+| :star: | Right Sibling Tree | :black_large_square: | [right-sibling-tree.py](https://github.com/das-jishu/algoexpert-data-structures-algorithms/blob/master/Very%20Hard/right-sibling-tree.py) |
+| :star: | All Kinds of Node Depths | :black_large_square: | [all-kinds-of-node-depths.py](https://github.com/das-jishu/algoexpert-data-structures-algorithms/blob/master/Very%20Hard/all-kinds-of-node-depths.py) |
+| :star: | Compare Leaf Traversal | :black_large_square: | [compare-leaf-traversal.py](https://github.com/das-jishu/algoexpert-data-structures-algorithms/blob/master/Very%20Hard/compare-leaf-traversal.py) |
+| :star: | Max Profit With K Transactions | :black_large_square: | [max-profit-with-k-transactions.py](https://github.com/das-jishu/algoexpert-data-structures-algorithms/blob/master/Very%20Hard/max-profit-with-k-transactions.py) |
+| :star: | Palindrome Partitioning Min Cuts | :black_large_square: | [palindrome-partitioning-min-cuts.py](https://github.com/das-jishu/algoexpert-data-structures-algorithms/blob/master/Very%20Hard/palindrome-partitioning-min-cuts.py) |
+| :star: | Longest Increasing Subsequence | :black_large_square: | [longest-increasing-subsequence.py](https://github.com/das-jishu/algoexpert-data-structures-algorithms/blob/master/Very%20Hard/longest-increasing-subsequence.py) |
+| :star: | Longest String Chain | :black_large_square: | [longest-string-chain.py](https://github.com/das-jishu/algoexpert-data-structures-algorithms/blob/master/Very%20Hard/longest-string-chain.py) |
+| :star: | Square Of Zeroes | :black_large_square: | [square-of-zeroes.py](https://github.com/das-jishu/algoexpert-data-structures-algorithms/blob/master/Very%20Hard/square-of-zeroes.py) || :star: | Knuth Morris Pratt Algorithm | :black_large_square: | [knuth-morris-pratt-algorithm.py](https://github.com/das-jishu/algoexpert-data-structures-algorithms/blob/master/Very%20Hard/knuth-morris-pratt-algorithm.py) |
+| :star: | A Star Algorithm | :black_large_square: | [a-star-algorithm.py](https://github.com/das-jishu/algoexpert-data-structures-algorithms/blob/master/Very%20Hard/a-star-algorithm.py) || :star: | Rectangle Mania | :black_large_square: | [rectangle-mania.py](https://github.com/das-jishu/algoexpert-data-structures-algorithms/blob/master/Very%20Hard/rectangle-mania.py) |   
+| :star: | Detect Arbitrage | :black_large_square: | [detect-arbitrage.py](https://github.com/das-jishu/algoexpert-data-structures-algorithms/blob/master/Very%20Hard/detect-arbitrage.py) || :star: | Two Edge Connected Graph | :black_large_square: | [two-edge-connected-graph.py](https://github.com/das-jishu/algoexpert-data-structures-algorithms/blob/master/Very%20Hard/two-edge-connected-graph.py) |
+| :star: | Airport Connections | :black_large_square: | [airport-connections.py](https://github.com/das-jishu/algoexpert-data-structures-algorithms/blob/master/Very%20Hard/airport-connections.py) |
+| :star: | Merge Sorted Arrays | :black_large_square: | [merge-sorted-arrays.py](https://github.com/das-jishu/algoexpert-data-structures-algorithms/blob/master/Very%20Hard/merge-sorted-arrays.py) |
+| :star: | LRU Cache | :black_large_square: | [lRU-cache.py](https://github.com/das-jishu/algoexpert-data-structures-algorithms/blob/master/Very%20Hard/lRU-cache.py) |
+| :star: | Rearrange Linked List | :black_large_square: | [rearrange-linked-list.py](https://github.com/das-jishu/algoexpert-data-structures-algorithms/blob/master/Very%20Hard/rearrange-linked-list.py) |
+| :star: | Linked List Palindrome | :black_large_square: | [linked-list-palindrome.py](https://github.com/das-jishu/algoexpert-data-structures-algorithms/blob/master/Very%20Hard/linked-list-palindrome.py) |
+| :star: | Zip Linked List | :black_large_square: | [zip-linked-list.py](https://github.com/das-jishu/algoexpert-data-structures-algorithms/blob/master/Very%20Hard/zip-linked-list.py) |   
+| :star: | Node Swap | :black_large_square: | [node-swap.py](https://github.com/das-jishu/algoexpert-data-structures-algorithms/blob/master/Very%20Hard/node-swap.py) |
+| :star: | Number of Binary Tree Topologies | :black_large_square: | [number-of-binary-tree-topologies.py](https://github.com/das-jishu/algoexpert-data-structures-algorithms/blob/master/Very%20Hard/number-of-binary-tree-topologies.py) |
+| :star: | Non Attacking Queens | :black_large_square: | [non-attacking-queens.py](https://github.com/das-jishu/algoexpert-data-structures-algorithms/blob/master/Very%20Hard/non-attacking-queens.py) |
+| :star: | Merge Sort | :black_large_square: | [merge-sort.py](https://github.com/das-jishu/algoexpert-data-structures-algorithms/blob/master/Very%20Hard/merge-sort.py) |
+| :star: | Count Inversions | :black_large_square: | [count-inversions.py](https://github.com/das-jishu/algoexpert-data-structures-algorithms/blob/master/Very%20Hard/count-inversions.py) || :star: | Smallest Substring Containing | :black_large_square: | [smallest-substring-containing.py](https://github.com/das-jishu/algoexpert-data-structures-algorithms/blob/master/Very%20Hard/smallest-substring-containing.py) |
+| :star: | Longest Balanced Substring | :black_large_square: | [longest-balanced-substring.py](https://github.com/das-jishu/algoexpert-data-structures-algorithms/blob/master/Very%20Hard/longest-balanced-substring.py) |
 
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