int searchhelp(int * arr, int low, int high, int key)
{
if (low > high)
{
return -1;
}
else
{
int i = (low+high)/2;
if (arr[i] == key)
{
return i;
}
else
{
if (arr[i] > key)
{
return (searchhelp(arr,low,i-1,key));
}
else
{
return (searchhelp(arr,i+1,high,key));
}
}
}
}
int searchhelp(int* arr, int low, int high, int key){
if(low >= high){
return -1;
}
int ind = (low+high)/2;
if(arr[ind] == key){
return ind;
}
if(arr[ind] > key){
return searchhelp(arr, low, ind-1, key);
}
return searchhelp(arr, ind+1, high, key);
}
/**
* Use binary search to find 'key' in a sorted array of integers
*
* Arguments:
*
* arr The array to search. Must be sorted ascending. You do not need
* to check. This array is from the result of your sort
* function. Make sure your sort function is correct before you
* start writing this function.
*
* length Number of elements in the array
* key Value to search for in arr
*
* Returns:
* The index of 'key', or -1 if key is not found.
*
* Since the array is sorted, you can quickly discard many elements by
* comparing the key and the element at the center of the array. If
* the key is the same as this element, you have found the index. If
* the key is greater than this element, you can discard the first
* half of the array. If the key is smaller, you can discard the
* second half of the array. Now you have only half of the array to
* search. Continue this procedure until either you find the index or
* it is impossible to find a match.
*
* Your solution MUST use recursive function (or functions)
*
* Don't forget that arrays are 'zero-indexed'. Also, you must
* use a binary search to pass this question.
*
* You will receive no point if you do the following because it is not
* binary search. This is called linear search because it checks
* every element.
*
* int ind;
* for (ind = 0; ind < length; ind ++)
* {
* if (arr[ind] == key)
* {
* return ind;
* }
* }
* return -1;
*/
int search(int * arr, int length, int key)
{
return searchhelp(arr, 0, length, key);
}
/**
* Use binary search to find 'key' in a sorted array of integers
*
* Arguments:
*
* arr The array to search. Must be sorted ascending. You do not need
* to check. This array is from the result of your sort
* function. Make sure your sort function is correct before you
* start writing this function.
*
* length Number of elements in the array
* key Value to search for in arr
*
* Returns:
* The index of 'key', or -1 if key is not found.
*
* Since the array is sorted, you can quickly discard many elements by
* comparing the key and the element at the center of the array. If
* the key is the same as this element, you have found the index. If
* the key is greater than this element, you can discard the first
* half of the array. If the key is smaller, you can discard the
* second half of the array. Now you have only half of the array to
* search. Continue this procedure until either you find the index or
* it is impossible to find a match.
*
* Your solution MUST use recursive function (or functions)
*
* Don't forget that arrays are 'zero-indexed'. Also, you must
* use a binary search to pass this question.
*
* You will receive no point if you do the following because it is not
* binary search. This is called linear search because it checks
* every element.
*
* int ind;
* for (ind = 0; ind < length; ind ++)
* {
* if (arr[ind] == key)
* {
* return ind;
* }
* }
* return -1;
*/
int search(int * arr, int length, int key)
{
int searchhelp(int*,int,int,int);
return (searchhelp(arr,0,length-1,key));
}
