QUICKSORT

Quicksort.cpp

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+#include <iostream>
+#include <algorithm>
+
+using namespace std;
+
+void show(int a[],int n)
+{
+	for(int i = 0; i < n; ++i)
+		cout << a[i] << " ";
+}
+
+int main()
+{
+	int a[100],n;
+	cin>>n;
+	for(int i=0;i<n;i++)
+        cin>>a[i];
+	cout << "\n The array before sorting is : ";
+	show(a,n);
+
+	sort(a, a+n);
+
+	cout << "\n\n The array after sorting is : ";
+	show(a,n);
+
+	return 0;
+
+}

mergesort.c

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+
+/* C program for Merge Sort */
+#include<stdlib.h>
+#include<stdio.h>
+
+// Merges two subarrays of arr[].
+// First subarray is arr[l..m]
+// Second subarray is arr[m+1..r]
+void merge(int arr[], int l, int m, int r)
+{
+    int i, j, k;
+    int n1 = m - l + 1;
+    int n2 =  r - m;
+
+    /* create temp arrays */
+    int L[n1], R[n2];
+
+    /* Copy data to temp arrays L[] and R[] */
+    for (i = 0; i < n1; i++)
+        L[i] = arr[l + i];
+    for (j = 0; j < n2; j++)
+        R[j] = arr[m + 1+ j];
+
+    /* Merge the temp arrays back into arr[l..r]*/
+    i = 0; // Initial index of first subarray
+    j = 0; // Initial index of second subarray
+    k = l; // Initial index of merged subarray
+    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 */
+void mergeSort(int arr[], int l, int r)
+{
+    if (l < r)
+    {
+        // Same as (l+r)/2, but avoids overflow for
+        // large l and h
+        int m = l+(r-l)/2;
+
+        // Sort first and second halves
+        mergeSort(arr, l, m);
+        mergeSort(arr, m+1, r);
+
+        merge(arr, l, m, r);
+    }
+}
+
+/* UTILITY FUNCTIONS */
+/* Function to print an array */
+void printArray(int A[], int size)
+{
+    int i;
+    for (i=0; i < size; i++)
+        printf("%d ", A[i]);
+    printf("\n");
+}
+
+/* Driver program to test above functions */
+int main()
+{
+    int arr[1000],n;
+    scanf("%d",&n);
+    for(int i=0;i<n;i++)
+    {
+        scanf("%d",arr[i]);
+    }
+    int arr_size = n;
+
+    printf("Given array is \n");
+    printArray(arr, arr_size);
+
+    mergeSort(arr, 0, arr_size - 1);
+
+    printf("\nSorted array is \n");
+    printArray(arr, arr_size);
+    return 0;
+}