another shell-sort implementation

sorting/shell_sort2.c

@@ -0,0 +1,78 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <time.h>
+
+#define ELEMENT_NR 20000
+#define ARRAY_LEN(x) (sizeof(x) / sizeof((x)[0]))
+
+void show_data(int arr[], int len)
+{
+    int i;
+
+    for (i = 0; i < len; i++)
+        printf("%3d ", arr[i]);
+    printf("\n");
+}
+
+void swap(int *a, int *b)
+{
+    int tmp;
+
+    tmp = *a;
+    *a = *b;
+    *b = tmp;
+}
+
+/**
+ * Optimized algorithm - takes half the time as other
+ **/
+void shell_sort(int array[], int LEN)
+{
+    const int gaps[] = {701, 301, 132, 57, 23, 10, 4, 1};
+    const int gap_len = 8;
+    int i, j, g;
+
+    for (g = 0; g < gap_len; g++)
+    {
+        int gap = gaps[g];
+        for (i = gap; i < LEN; i++)
+        {
+            int tmp = array[i];
+
+            for (j = i; j >= gap && (array[j - gap] - tmp) > 0; j -= gap)
+                array[j] = array[j - gap];
+            array[j] = tmp;
+        }
+    }
+#ifdef DEBUG
+    for (i = 0; i < LEN; i++)
+        printf("%s\t", data[i]);
+#endif
+}
+
+int main(int argc, char *argv[])
+{
+    int i;
+    int array[ELEMENT_NR];
+    int range = 500;
+    int size;
+    double time_spent;
+
+    srand(time(NULL));
+    for (i = 0; i < ELEMENT_NR; i++)
+        array[i] = rand() % range + 1;
+
+    size = ARRAY_LEN(array);
+
+    show_data(array, size);
+    clock_t t1 = clock();
+    shell_sort(array, size);
+    clock_t t2 = clock();
+
+    printf("Data Sorted\n");
+    show_data(array, size);
+
+    printf("Time spent sorting: %.4g s\n", (t2 - t1) / CLOCKS_PER_SEC);
+
+    return 0;
+}