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#include<stdio.h>
/* By comparison, binary search always chooses the middle of the remaining
* search space, discarding one half or the other, depending on the comparison
* between the key found at the estimated position and the key sought. The remaining
* search space is reduced to the part before or after the estimated position.
* The linear search uses equality only as it compares elements one-by-one from the start, ignoring any sorting.
* On average the interpolation search makes about log(log(n)) comparisons (if the elements
* are uniformly distributed), where n is the number of elements to be searched. In the worst case
* (for instance where the numerical values of the keys increase exponentially) it can make up to O(n) comparisons.
* In interpolation-sequential search, interpolation is used to find an item near the one being searched for,
* then linear search is used to find the exact item. */
int interpolationSearch(int arr[], int n, int key)
{
int low = 0, high = n - 1;
while (low <= high && key >= arr[low] && key <= arr[high]) {
/* Calculate the nearest posible position of key */
int pos = low + ((key - arr[low]) * (high - low)) / (arr[high] - arr[low]);
if (key > arr[pos])
low = pos + 1;
else if (key < arr[pos])
high = pos - 1;
else /* Found */
return pos;
}
/* Not found */
return -1;
}
int main()
{
int x;
int arr[] = {10, 12, 13, 16, 18, 19, 20, 21, 22, 23,
24, 33, 35, 42, 47};
int n = sizeof(arr)/sizeof(arr[0]);
printf("Array: ");
for(int i = 0; i < n; i++)
printf("%d ", arr[i]);
printf("\nEnter the number to be searched: ");
scanf("%d",&x); /* Element to be searched */
int index = interpolationSearch(arr, n, x);
/* If element was found */
if (index != -1)
printf("Element found at position: %d\n", index);
else
printf("Element not found.\n");
return 0;
}