// Bucket sort in C

#include <stdio.h>
#include <stdlib.h>

#define NARRAY 7 // Array size
#define NBUCKET 6 // Number of buckets
#define INTERVAL 10 // Each bucket capacity

struct Node {
int data;
struct Node *next;
};

void BucketSort(int arr[]);
struct Node *InsertionSort(struct Node *list);
void print(int arr[]);
void printBuckets(struct Node *list);
int getBucketIndex(int value);

// Sorting function
void BucketSort(int arr[]) {
int i, j;
struct Node **buckets;

// Create buckets and allocate memory size
buckets = (struct Node **)malloc(sizeof(struct Node *) * NBUCKET);

// Initialize empty buckets
for (i = 0; i < NBUCKET; ++i) {
buckets[i] = NULL;
}

// Fill the buckets with respective elements
for (i = 0; i < NARRAY; ++i) {
struct Node *current;
int pos = getBucketIndex(arr[i]);
current = (struct Node *)malloc(sizeof(struct Node));
current->data = arr[i];
current->next = buckets[pos];
buckets[pos] = current;
}

// Print the buckets along with their elements
for (i = 0; i < NBUCKET; i++) {
printf("Bucket[%d]: ", i);
printBuckets(buckets[i]);
printf("\n");
}

// Sort the elements of each bucket
for (i = 0; i < NBUCKET; ++i) {
buckets[i] = InsertionSort(buckets[i]);
}

printf("-------------\n");
printf("Bucktets after sorting\n");
for (i = 0; i < NBUCKET; i++) {
printf("Bucket[%d]: ", i);
printBuckets(buckets[i]);
printf("\n");
}

// Put sorted elements on arr
for (j = 0, i = 0; i < NBUCKET; ++i) {
struct Node *node;
node = buckets[i];
while (node) {
arr[j++] = node->data;
node = node->next;
}
}

return;
}

// Function to sort the elements of each bucket
struct Node *InsertionSort(struct Node *list) {
struct Node *k, *nodeList;
if (list == 0 || list->next == 0) {
return list;
}

nodeList = list;
k = list->next;
nodeList->next = 0;
while (k != 0) {
struct Node *ptr;
if (nodeList->data > k->data) {
struct Node *tmp;
tmp = k;
k = k->next;
tmp->next = nodeList;
nodeList = tmp;
continue;
}

for (ptr = nodeList; ptr->next != 0; ptr = ptr->next) {
  if (ptr->next->data > k->data)
    break;
}

if (ptr->next != 0) {
  struct Node *tmp;
  tmp = k;
  k = k->next;
  tmp->next = ptr->next;
  ptr->next = tmp;
  continue;
} else {
  ptr->next = k;
  k = k->next;
  ptr->next->next = 0;
  continue;
}

}
return nodeList;
}

int getBucketIndex(int value) {
return value / INTERVAL;
}

void print(int ar[]) {
int i;
for (i = 0; i < NARRAY; ++i) {
printf("%d ", ar[i]);
}
printf("\n");
}

// Print buckets
void printBuckets(struct Node *list) {
struct Node *cur = list;
while (cur) {
printf("%d ", cur->data);
cur = cur->next;
}
}

// Driver code
int main(void) {
int array[NARRAY] = {42, 32, 33, 52, 37, 47, 51};

printf("Initial array: ");
print(array);
printf("-------------\n");

BucketSort(array);
printf("-------------\n");
printf("Sorted array: ");
print(array);
return 0;
}