Create Merge Sort

algorithms/javascript/Merge Sort

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+// JavaScript program for Merge Sort
+
+//TC - O(N log(N))
+//SC - O(N)
+
+// Merges two subarrays of arr[].
+// First subarray is arr[l..m]
+// Second subarray is arr[m+1..r]
+function merge(arr, l, m, r)
+{
+	var n1 = m - l + 1;
+	var n2 = r - m;
+
+	// Create temp arrays
+	var L = new Array(n1); 
+	var R = new Array(n2);
+
+	// Copy data to temp arrays L[] and R[]
+	for (var i = 0; i < n1; i++)
+		L[i] = arr[l + i];
+	for (var j = 0; j < n2; j++)
+		R[j] = arr[m + 1 + j];
+
+	// Merge the temp arrays back into arr[l..r]
+
+	// Initial index of first subarray
+	var i = 0;
+
+	// Initial index of second subarray
+	var j = 0;
+
+	// Initial index of merged subarray
+	var k = l;
+
+	while (i < n1 && j < n2) {
+		if (L[i] <= R[j]) {
+			arr[k] = L[i];
+			i++;
+		}
+		else {
+			arr[k] = R[j];
+			j++;
+		}
+		k++;
+	}
+
+	// Copy the remaining elements of
+	// L[], if there are any
+	while (i < n1) {
+		arr[k] = L[i];
+		i++;
+		k++;
+	}
+
+	// Copy the remaining elements of
+	// R[], if there are any
+	while (j < n2) {
+		arr[k] = R[j];
+		j++;
+		k++;
+	}
+}
+
+// l is for left index and r is
+// right index of the sub-array
+// of arr to be sorted
+function mergeSort(arr,l, r){
+	if(l>=r){
+		return;
+	}
+	var m =l+ parseInt((r-l)/2);
+	mergeSort(arr,l,m);
+	mergeSort(arr,m+1,r);
+	merge(arr,l,m,r);
+}
+
+// Function to print an array
+function printArray( A, size)
+{
+	for (var i = 0; i < size; i++)
+	console.log( A[i] + " ");
+}
+
+
+var arr = [ 12, 11, 13, 5, 6, 7 ];
+	var arr_size = arr.length;
+
+	console.log( "Given array is ");
+	printArray(arr, arr_size);
+
+	mergeSort(arr, 0, arr_size - 1);
+
+	console.log( "Sorted array is ");
+	printArray(arr, arr_size);

algorithms/javascript/Quick Sort

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+// Quick sort in javascript
+
+//TC - O(N2)
+//SC - O(1)
+
+
+// Function to partition the array and return the partition index
+function partition(arr, low, high) {
+	// Choosing the pivot
+	let pivot = arr[high];
+
+	// Index of smaller element and indicates the right position of pivot found so far
+	let i = low - 1;
+
+	for (let j = low; j <= high - 1; j++) {
+		// If current element is smaller than the pivot
+		if (arr[j] < pivot) {
+			// Increment index of smaller element
+			i++;
+			[arr[i], arr[j]] = [arr[j], arr[i]]; // Swap elements
+		}
+	}
+
+	[arr[i + 1], arr[high]] = [arr[high], arr[i + 1]]; // Swap pivot to its correct position
+	return i + 1; // Return the partition index
+}
+
+// The main function that implements QuickSort
+function quickSort(arr, low, high) {
+	if (low < high) {
+		// pi is the partitioning index, arr[pi] is now at the right place
+		let pi = partition(arr, low, high);
+
+		// Separately sort elements before partition and after partition
+		quickSort(arr, low, pi - 1);
+		quickSort(arr, pi + 1, high);
+	}
+}
+
+// Driver code
+let arr = [10, 7, 8, 9, 1, 5];
+let N = arr.length;
+
+// Function call
+quickSort(arr, 0, N - 1);
+console.log("Sorted array:");
+console.log(arr.join(" "));
+
+//Output - 1 5 7 8 9 10