/*Sorting from little to large use List*/ #include <stdio.h> /* printf, scanf, NULL */ #include <stdlib.h> /* malloc, free */ struct node { int key; struct node *next; }; typedef struct node Node; Node *Head = NULL; Node *current; void Insert(int k) { Node *new_node; new_node = (Node *)malloc(sizeof(Node));//It is important but i can't understand now new_node->key = k; /* new node is inserted at the begining of the list*/ if ( Head == NULL || Head->key > k ) { new_node->next = Head; Head = new_node; } /* new node is inserted somewhere inside the list */ else { current = Head; /* Check what is the value in the next node , after the current node */ /* if it is larger, or if the next node not exist */ /* then we shuold insert the node to next current */ /* else, update current to point to next node */ while(1) { if( current->next == NULL || current->next->key > k ) { new_node->next = current->next; current->next = new_node; break; } else current = current->next; } } } Node *Delete(int k) { Node *answer; Node *current = Head; /* Handle the special case that the first node is to be deleted */ if ( Head != NULL && Head->key == k ) { Head = Head->next; return current; } else if ( Head != NULL && Head->key > k ) { return NULL; } while( current != NULL ) { /* check the next node is to be deleted */ if ( current->next != NULL && current->next->key == k ) { answer = current->next; current->next = current->next->next; return answer; } else if ( current->next != NULL && current->next->key > k ) return NULL; /* else, updated current */ current = current->next; } return NULL; /* if current is NULL, then k is not in the list, to return NULL */ } void Print() { if( Head == NULL ) printf("The list is empty! "); else { current = Head; while( current != NULL ) { printf("%d ", current->key); current = current->next; } printf(" "); } } int main() { Node *x; Insert(15); Insert(12); Insert(5); printf("15, 12, 5 are inserted"); Print(); x = Delete(5); if (x != NULL ) { printf("5 is deleted: "); free(x); Print(); } x = Delete(12); if ( x != NULL ) { printf("12 is deleted: "); free(x); Print(); } Insert(6); Insert(8); Insert(7); printf("6, 8, 7 is inserted: "); Print(); x = Delete(8); if ( x != NULL ) { printf("8 is deleted: "); free(x); Print(); } return 0; }