BUPT-homework/semester3/pset3/7-2-Binomial-Queue.c

#include <stdio.h>
#include <stdlib.h>
#define MAX 100

typedef struct Node {
  int data, degree;
  struct Node *child, *sibling, *parent;
} Node;

typedef struct list {
  int size;
  Node **arr;
} list;

list *newList() {
  list *new = malloc(sizeof(list));
  new->size = 0;
  new->arr = malloc(sizeof(Node *) * MAX);
  return new;
}

void pushBack(list *l, Node *new) { l->arr[l->size++] = new; }

void erase(list *l, int loc) {
  for (int i = loc; i < l->size - 1; i++) {
    l->arr[i] = l->arr[i + 1];
  }
  // remember this:
  l->size--;
}

void swapNode(Node *l, Node *r) {
  Node *tmp = malloc(sizeof(Node));
  *tmp = *l;
  *l = *r;
  *r = *tmp;
}

Node *newNode(int val) {
  Node *new = malloc(sizeof(Node));

  new->data = val;
  new->degree = 0;
  new->child = new->parent = new->sibling = NULL;

  return new;
}

list *unionList(list *l1, list *l2) {
  list *l = newList();

  int i = 0, j = 0;

  while (i < l1->size && j < l2->size) {
    // push the one with smaller degree first
    if (l1->arr[i]->degree <= l2->arr[j]->degree) {
      pushBack(l, l1->arr[i]);
      i++;
    } else {
      pushBack(l, l2->arr[j]);
      j++;
    }
  }

  while (i < l1->size) {
    pushBack(l, l1->arr[i]);
    i++;
  }

  while (j < l2->size) {
    pushBack(l, l2->arr[j]);
    j++;
  }
  return l;
}

Node *merge(Node *l, Node *r) {
  if (l->data > r->data) {
    swapNode(l, r);
  }

  // sub-node might have a sibling, but head node doesn't have one.
  r->parent = l;
  r->sibling = l->child;

  l->child = r;
  l->degree++;

  return l;
}

list *adjust(list *l) {
  if (l->size <= 1) {
    return l;
  }

  int i = 0, j = 0, k = 0;

  if (l->size == 2) {
    j = i + 1;
    k = l->size;
  } else {
    j++;
    k = j + 1;
  }

  // can't use i != size here, since the list will shrink.
  while (i < l->size) {
    // only one element remains, if j > size, then i == size
    if (j == l->size) {
      i++;
    } else if (l->arr[i]->degree < l->arr[j]->degree) {
      i++;
      j++;
      if (k < l->size) {
        k++;
      }
    } else if (k < l->size && l->arr[i]->degree == l->arr[j]->degree &&
               l->arr[i]->degree == l->arr[k]->degree) {
      // at most 3 same degrees, because of binary operations
      i++;
      j++;
      k++;
    } else if (l->arr[i]->degree == l->arr[j]->degree) {
      l->arr[i] = merge(l->arr[i], l->arr[j]);
      erase(l, j);
      // doesn't have to move k
    }
  }

  return l;
}

list *insertTree(list *l, Node *tree) {
  list *temp = newList();

  pushBack(temp, tree);

  temp = unionList(l, temp);

  return adjust(temp);
}

list *insert(list *l, int key) {
  Node *temp = newNode(key);
  return insertTree(l, temp);
}

void traverseLevel(Node* h, int level) {
  if (h) {
    traverseLevel(h->sibling, level);
    if (level == 1) {
      printf("%d,", h->data);
    } else {
      traverseLevel(h->child, level - 1);
    }
  }
}

void printTree(Node *h) {
  int i = 0;
  for (Node* ptr = h; ptr != NULL; ptr = ptr->child) {
    i++;
    traverseLevel(h, i);
  }
}

void printHeap(list *l, int k) {
  int present = 0;
  for (int i = 0; i < l->size; i++) {
    if (l->arr[i]->degree == k) {
      printTree(l->arr[i]);
      present = 1;
    }
  }

  if (present == 0) {
    printf("0,");
  }
}

int getDigits(int i) {
  int count = 0;
  while (i) {
    count ++;
    i /= 10;
  }

  return count;
}

int main(void) {
  list *l = newList();

  char buf[MAX];
  scanf("%s", buf);
  int tmp, offset = 0;

  while (sscanf(buf + offset, "%d,", &tmp) != EOF) {
    // printf("%d is scanned, offset: %d\n", tmp, offset);
    l = insert(l, tmp);
    offset += getDigits(tmp) + 1;
  }

  int treeNum;

  scanf("%d", &treeNum);

  printHeap(l, treeNum);

  return 0;
}