Question

Implement a binary search function that takes an integer query key and determines whether it is in a sorted array of n integers. It should return the index of the key, if found, otherwise it should return a negative number. You should implement the function both iteratively and recursively to be sure you really understand the algorithm. Just for the fun of it, you might want to verify the O(log(n)) complexity of your function by counting the number of comparisons performed for each query. For example, it should never do more than 10 comparisons for n=1000 or more than 20 comparisons for n=1,000,000.

(Using C language only please!)

Answer 1

Below are the required codes in C

int iterativeBinarySearch(int arr[], int n, int target) {
int count = 0;
int left = 0, right = n-1, mid;
while (left <= right) {
mid = (left + right) / 2;
if (arr[mid] == target)
{
printf("The number of comparisons are : %d",count)
return mid;
}
else if (arr[mid] < target)
left = mid+1;
else
right = mid-1;
count++;
}
return -1;
}

int recursiveBinarySearch(int arr[],int n, int target,int left,int right,int count){

if(right < left)
return -1;
int mid = (left+right)/2;
if(arr[mid] == target){
printf("The number of comparisons are : %d",count)
return mid;
}
else if (arr[mid] < target)
return recursiveBinarySearch(arr,n,target,mid+1,right,count+1);
else
return recursiveBinarySearch(arr,n,target,left,mid-1,count+1);

}
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