Merge Sort Program with Complexity Analysis

Author: msindev

Merge Sort/MergeSort.c

@@ -0,0 +1,77 @@
+#include <stdio.h>
+#include <stdlib.h>
+int count;
+void mergesort(int[], int, int);
+void merge(int[], int, int, int);
+int main()
+{
+    int a[1200],b[1200],c[1200],c1,c2,c3,i,j,n;
+    printf("Enter the number of elements: ");
+    scanf("%d",&n);
+    printf("Enter the elements: ");
+    for(i = 0; i < n; i++)
+        scanf("%d",&a[i]);
+    mergesort(a,0,n-1);
+    printf("Sorted Array:");
+    for(i=0;i<n;i++)
+        printf("%d ",a[i]);
+    printf("\nTime Complexity Analysis: \n");
+    printf("SIZE\tASCENDING\tDESCENDING\tRANDOM\n");
+    for(i=16;i<=1024;i*=2)
+    {
+        for(j=0;j<i;j++)
+        {
+            a[j]=j;
+            b[j]=i-j;
+            c[j]=rand()%(i+1);
+        }
+        count = 0;
+        mergesort(a,0,i-1);
+        c1=count;
+        count=0;
+        mergesort(b,0,i-1);
+        c2=count;
+        count=0;
+        mergesort(c,0,i-1);
+        c3=count;
+        printf("%d\t%d\t\t%d\t\t%d\n",i,c1,c2,c3);
+    }
+    return 0;
+}
+
+void mergesort(int a[], int low, int high)
+{
+    int mid;
+    if(low<high)
+    {
+        mid=(low+high)/2;
+        mergesort(a,low,mid);
+        mergesort(a,mid+1,high);
+        merge(a,low,mid,high);
+    }
+}
+
+void merge(int a[], int low, int mid, int high)
+{
+    int b[1200],i=low,j=mid+1,k=low;
+    while(i<=mid && j<=high)
+    {
+        if(a[i]<a[j])
+            b[k++]=a[i++];
+        else
+            b[k++]=a[j++];
+        count++;
+    }
+    while(i<=mid)
+    {
+        b[k++]=a[i++];
+        count++;
+    }
+    while(j<=high)
+    {
+        b[k++]=a[j++];
+        count++;
+    }
+    for(k=low;k<=high;k++)
+        a[k]=b[k];
+}