68 lines
1.6 KiB
C++
68 lines
1.6 KiB
C++
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/* Program to demonstrate recursive merge sort */
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#include <stdio.h>
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#include <conio.h>
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void mergesort(int x[ ], int lb, int ub) ;
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void merge(int x[ ], int lb1, int ub1, int ub2) ;
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void show(int x[ ], int lb, int ub) ;
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void main()
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{
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int i, n, x[20] ;
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clrscr() ;
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printf("Enter the number of elements: ") ;
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scanf("%d",&n) ;
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printf("Enter the elements:\n") ;
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for(i=0 ; i<n ; i++)
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scanf("%d",&x[i]) ;
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mergesort(x,0,n-1) ;
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printf("Sorted array is as shown:\n") ;
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for(i=0 ; i<n ; i++)
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printf("%d ", x[i]) ;
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getch() ;
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}
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void mergesort(int x[ ], int lb, int ub)
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{
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int mid ;
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if(lb<ub)
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{
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mid=(lb+ub)/2 ;
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mergesort(x,lb,mid) ;
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mergesort(x,mid+1,ub) ;
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merge(x,lb,mid,ub) ;
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}
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}
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void merge(int x[ ], int lb1, int ub1, int ub2)
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{
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int temp[50], i, j, k ;
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i=lb1 ;
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j=ub1+1 ;
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k=0 ;
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while(i<=ub1&&j<=ub2)
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if(x[i]<x[j]) /* use > for descending order */
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temp[k++]=x[i++] ;
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else
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temp[k++]=x[j++] ;
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while(i<=ub1)
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temp[k++]=x[i++] ;
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while(j<=ub2)
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temp[k++]=x[j++] ;
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for(i=lb1, j=0 ; i<=ub2 ; i++, j++)
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x[i]=temp[j] ;
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show(x,lb1,ub2) ;
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}
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void show(int x[ ], int lb, int ub)
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{
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int i ;
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for(i=lb ; i<=ub ; i++)
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printf("%d ", x[i]) ;
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printf("\n\n") ;
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}
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/* The method show() is optional. It is written to show output of each pass. It may not be written in theory exam. It is required only in practical exams */
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