BUPT-homework/semester2/pset2/4-splitNShift.c

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

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

Node *constructLinkedList();
Node *appendLinkedList(Node *node, int data);
void deleteLinkedList(Node *head);
Node *segmentLinkedList(Node *head, Node **nextHead, int segLen);
// returns the head of segmented Linked list, writes the head of next linked
// list to *nextHead
void connectLinkedList(Node *head1, Node *head2);
// appends list2 to the end of list1
void printLinkedList(Node *head);

int main(void) {
  Node *head = constructLinkedList();
	/* printLinkedList(head); */

  int s1, t1, s2, t2;
  scanf("%d%d%d%d", &s1, &t1, &s2, &t2);

  Node *tmp;
  Node *ptr = head;
  // start to iterate to s1
  for (int i = 1; i < s1; i++) {
    if (i == s1 - 1) {
      tmp = ptr->next;
      ptr->next = NULL;
      ptr = tmp;
    } else {
      ptr = ptr->next;
    }
  }
  Node *seg1, *seg2 = NULL, *seg3, *seg4 = NULL;
  // get the first segment
  seg1 = segmentLinkedList(ptr, &seg2, t1 - s1);
	ptr = seg2;

  for (int i = 0; i < s2 - t1 - 1; i++) {
    if (i == s2 - t1 - 2) {
      tmp = (Node*)(ptr->next);
      ptr->next = NULL;
      ptr = tmp;
    } else {
      ptr = ptr->next;
    }
  }
  seg3 = segmentLinkedList(ptr, &seg4, t2 - s2);

  // special cases:
  // head == seg1
  // seg2 == seg3
  // seg4 == NULL

	Node *newHead = head;

  if (head != seg1) {
    connectLinkedList(head, seg3);
  } else {
		newHead = seg3;
	}
  if (seg2 != seg3) {
    connectLinkedList(seg3, seg2);
  }
  connectLinkedList(seg2, seg1);
  if (seg4 != NULL) {
    connectLinkedList(seg1, seg4);
  }

	printf("The new list is:");
	printLinkedList(newHead);

  deleteLinkedList(newHead);
  return 0;
}

Node *constructLinkedList() {
  int buf;
  Node *head = malloc(sizeof(Node));
  scanf("%d", &buf);
  head->data = buf;
  head->next = NULL;

  Node *ptr = head;

  scanf("%d", &buf);
  while (buf != -1) {
    ptr = appendLinkedList(ptr, buf);
    scanf("%d", &buf);
  }

  return head;
}

Node *appendLinkedList(Node *node, int data) {
  Node *new = malloc(sizeof(Node));

  new->next = NULL;
  new->data = data;

  node->next = new;

  return new;
}

void deleteLinkedList(Node *head) {
  if (head == NULL) {
    return;
  } else {
    deleteLinkedList(head->next);
    free(head);
  }
}

Node *segmentLinkedList(Node *head, Node **nextHead, int segLen) {
  Node *ptr = head;
  for (int i = 0; i < segLen; i++) {
    ptr = ptr->next;
  }

  if (ptr->next != NULL) {
    *nextHead = ptr->next;
  }
  ptr->next = NULL;

  return head;
}

void connectLinkedList(Node *head1, Node *head2) {
  Node *ptr = head1;

  while (ptr->next != NULL) {
    ptr = ptr->next;
  }

  ptr->next = head2;
}

void printLinkedList(Node *head) {
	if (head != NULL)
		printf("%d", head->data);

	Node *ptr = head;
	ptr = head->next;

	while (ptr != NULL) {
		printf(" %d", ptr->data);
		ptr = ptr->next;
	}
}