Updated README and partially solved (timing out on heavy tests) the countInversions.

Author: jonasraoni

README.md

@@ -75,19 +75,20 @@ Note: Few codes were solved in C# (I've written them a long time ago), I'll conv
 
 ### [Arrays](data-structures/arrays)
 
-- [Array Manipulation](data-structures/arrays/arrayManipulation.js)
 - [2D Array - DS](data-structures/arrays/hoursglassSum.js)
+- [Array Manipulation](data-structures/arrays/arrayManipulation.js)
 ### [Linked Lists](data-structures/linked-lists)
 
 - [Find Merge Point Of Two Lists](data-structures/linked-lists/findMergeNode.js)
 - [Insert A Node At A Specific Position In A Linked List](data-structures/linked-lists/insertNodeAtPosition.js)
-- [Reverse A Doubly Linked List](data-structures/linked-lists/reverse.js)
 - [Inserting a Node Into a Sorted Doubly Linked List](data-structures/linked-lists/sortedInsert.js)
+- [Reverse A Doubly Linked List](data-structures/linked-lists/reverse.js)
 
 ### [Trees](data-structures/trees)
 
-- [Tree: Height of a Binary Tree](data-structures/trees/height.js)
 - [Binary Search Tree : Lowest Common Ancestor](data-structures/trees/lca.js)
+- [Tree: Height of a Binary Tree](data-structures/trees/height.js)
+
 ## [Functional Programming](functional-programming)
 
 - [Solve Me First FP](functional-programming/introduction/solveMeFirst.cs)
@@ -96,13 +97,15 @@ Note: Few codes were solved in C# (I've written them a long time ago), I'll conv
 ## [Tutorials](tutorials)
 
 ### [Cracking The Code Interview](tutorials/cracking-the-code-interview)
-
+Merge Sort: Counting Inversions
+- [Arrays: Left Rotation](tutorials/cracking-the-code-interview/rotLeft.js)
+- [Hash Tables: Ice Cream Parlor](tutorials/cracking-the-code-interview/whatFlavors.js)
 - [Hash Tables: Ransom Note Solution](tutorials/cracking-the-code-interview/checkMagazine.js)
-- [Sorting: Comparator](tutorials/cracking-the-code-interview/compare.js)
-- [Sorting: Bubble Sort](tutorials/cracking-the-code-interview/countSwaps.js)
-- [Recursion: Fibonacci Numbers](tutorials/cracking-the-code-interview/fibonacci.js)
 - [Linked Lists: Detect a Cycle](tutorials/cracking-the-code-interview/has_cycle.js)
+- [Merge Sort: Counting Inversions](tutorials/cracking-the-code-interview/countInversions.js)
+- [Recursion: Fibonacci Numbers](tutorials/cracking-the-code-interview/fibonacci.js)
+- [Sorting: Bubble Sort](tutorials/cracking-the-code-interview/countSwaps.js)
+- [Sorting: Comparator](tutorials/cracking-the-code-interview/compare.js)
 - [Strings: Making Anagrams](tutorials/cracking-the-code-interview/makeAnagram.js)
 - [Time Complexity: Primality](tutorials/cracking-the-code-interview/primality.js)
-- [Arrays: Left Rotation](tutorials/cracking-the-code-interview/rotLeft.js)
-- [Hash Tables: Ice Cream Parlor](tutorials/cracking-the-code-interview/whatFlavors.js)
+

tutorials/cracking-the-code-interview/countInversions.js

@@ -0,0 +1,26 @@
+//+ Jonas Raoni Soares Silva
+//@ http://raoni.org
+
+// Currently failing at the heavy tests ;_;
+// It's clear that I have to find a way to avoid updating the original array, but I need some free time to think about it
+
+function countInversions(arr) {
+	const binarySearch = (o, v, i) => {
+		let h = o.length,
+			l = i - 1,
+			m;
+		while (h - l > 1)
+			if (o[m = h + l >> 1] < v) l = m;
+			else h = m;
+		return h;
+	};
+	let inversions = 0;
+	for (let l = arr.length, i = arr.length; --i;)
+		if (arr[i - 1] > arr[i]) {
+			const insert = binarySearch(arr, arr[i - 1], i);
+			for (let j = i - 1; ++j < insert;)
+				[arr[j], arr[j - 1]] = [arr[j - 1], arr[j]];
+			inversions += insert - i;
+		}
+	return inversions;
+}