Write a C Program That performing Merge Sort(Sorting Techniues)

1:  #include<stdio.h>  
2:  #include<conio.h>  
3:  #define MAX 20  
4:  void mergesort(int a[],int low,int high);  
5:  void merge(int a[],int beg,int mid,int end);  
6:  void display(int a[],int num);  
7:  void main()  
8:  {  
9:   int n,i,a[MAX];  
10:   clrscr();  
11:   printf("Enter the number of elements (<MAX )\n");  
12:   scanf("%d",&n);  
13:   printf("Enter the elements\n");  
14:   for(i=0;i<n;i++)  
15:   {  
16:   scanf("%d",&a[i]);  
17:   }  
18:   printf("\nArray elements before sorting are:\n");  
19:   display(a,n);  
20:   mergesort(a,0,n-1);  
21:   printf("\nArray elements after sorting are:\n");  
22:   display(a,n);  
23:   getch();  
24:  }  
25:  void mergesort(int a[],int low,int high)  
26:  {  
27:   int mid;  
28:   if(low<high)  
29:   {  
30:   mid=(low+high)/2;  
31:   mergesort(a,low,mid);  
32:   mergesort(a,mid+1,high);  
33:   merge(a,low,mid,high);  
34:   }  
35:  }  
36:  void merge(int a[],int beg, int mid,int end)  
37:  {  
38:   int temp,b[MAX],left,right,i;  
39:   left=beg;  
40:   right=mid+1;  
41:   temp=beg;  
42:   while((left<=mid) && (right<=end))  
43:   {  
44:   if(a[left]<a[right])  
45:   {  
46:    b[temp]=a[left];  
47:    left=left+1;  
48:   }  
49:   else  
50:   {  
51:    b[temp]=a[right];  
52:    right=right+1;  
53:   }  
54:   temp=temp+1;  
55:   }  
56:   while(left<=mid)  
57:   {  
58:   b[temp]=a[left];  
59:   left=left+1;  
60:   temp=temp+1;  
61:   }  
62:   while(right<=end)  
63:   {  
64:   b[temp]=a[right];  
65:   right=right+1;  
66:   temp=temp+1;  
67:   }  
68:   for(i=beg;i<=end;i++)  
69:   {  
70:   a[i]=b[i];  
71:   }  
72:  }  
73:  void display(int a[],int num)  
74:  {  
75:   int i;  
76:   for(i=0;i<num;i++)  
77:   {  
78:   printf("%d\t",a[i]);  
79:   }  
80:  }