TOPIC :-

MERGE SORT

B A S I C C O N C E P T O F M E R G E S O R T

I. Uses divide and conquer technique.

II. array is divided into sub-array.

III. Sub-arrays merged to get sorted result.

DIVIDE AND CONQUER

Divide and conquer method for algorithm design:

• Divide: Large problem is divided into sub-problems

• Conquer: recursively solve the sub-problems

• Combine: • Take the solutions to the sub-problems• “merge” these solutions into final solution

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DRY RUN OF PROGRAM

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AT THE END SORTED

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MERGING FUNCTION void merge ( int , int , int ) ;

void merge _ sort(int low , int high)

{

int mid;

if(low<high)

{

mid=( low + high)/2 ;

merge _ sort ( low , mid) ;

merge _ sort(mid+1,high);

merge ( low , mid , high) ;

}

}

IMPLEMENTATION

SUMMARY OF SORTING ALGORITHMS

Algorithm Time Notes

selection-sort O(n2) in-place slow (good for small inputs)

insertion-sort O(n2) in-place slow (good for small inputs)

quick-sort O(n log n) expected

in-place, randomized fastest (good for large inputs)

merge-sort O (n log n) sequential data access fast (good for huge inputs)

ANY QUESTION…