## C, search, jump_search.c

``````/**
* @file jump_search.c
* @brief Implementation of [jump
* search](https://en.wikipedia.org/wiki/Jump_search) algorithm.
*/
#include <assert.h>
#include <math.h>
#include <stdio.h>

/**
* @brief Macro to return the minimum of two values
*/
#define min(X, Y) ((X) < (Y) ? (X) : (Y))

/**
* @brief Implement Jump-search algorithm
*
* @param [in] arr Array to search within
* @param x value to search for
* @param n length of array
* @return index where the value was found
*/
int jump_search(const int *arr, int x, size_t n)
{
int step = floor(sqrt(n));
int prev = 0;

while (arr[min(step, n) - 1] < x)
{
prev = step;
step += floor(sqrt(n));
if (prev >= n)
{
return -1;
}
}

while (arr[prev] < x)
{
prev = prev + 1;
if (prev == min(step, n))
{
return -1;
}
}
if (arr[prev] == x)
{
return prev;
}
return -1;
}

/**
* @brief Test implementation of the function
*
*/
void test()
{
int arr[] = {0, 1, 1, 2, 3, 5, 8, 13, 21, 34, 55, 89, 144, 233, 377, 610};
size_t n = sizeof(arr) / sizeof(int);

int x = 55;
printf("Test 1.... ");
int index = jump_search(arr, x, n);
assert(index == 10);
printf("passed\nTest 2.... ");
x = 56;
index = jump_search(arr, x, n);
assert(index == -1);
printf("passed\nTest 3.... ");
x = 13;
index = jump_search(arr, x, n);
assert(index == 7);
printf("passed\n");
}

/**
* @brief Main function
*/
int main()
{
test();
return 0;
}
``````