C语言数据结构学习——单链表

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


typedef struct SingleLinkTable
{
    int elem;
    struct SingleLinkTable *next;
} SingleLinkTable;

/**
 * @brief 
 * create single link table
 * @return SingleLinkTable* 
 */
SingleLinkTable * initSingleLink(){
    // create a head node
    SingleLinkTable * p = (SingleLinkTable*)malloc(sizeof(SingleLinkTable));
    // declare a pointer to the head node for traversing the linked list
    SingleLinkTable * temp = p;
    // create link table
    for(int i = 1;i < 5; i ++){
        SingleLinkTable *a = (SingleLinkTable*)malloc(sizeof(SingleLinkTable));
        a->elem = i;
        a->next = NULL;
        temp->next = a;
        temp = temp->next;
    }
    return p;
}

/**
 * @brief 
 * insert element
 * @param p         source link table
 * @param elem      insert data
 * @param add       insert site
 * @return SingleLinkTable* 
 */
SingleLinkTable * insertElement(SingleLinkTable * p, int elem, int add){
    // create a temporary node
    SingleLinkTable * temp = p;
    // the first, we need find the upper node for insert site
    for(int i = 1;i < add; i ++){
        temp = temp->next;
        if(temp == NULL){
            printf("the insert site is not permit\n");
            return p;
        }
    }
    // create the insert node c
    SingleLinkTable * c = (SingleLinkTable*)malloc(sizeof(SingleLinkTable));
    c->elem = elem;
    // insert node to the link table
    c->next = temp->next;
    temp->next = c;
    return p;
}

/**
 * @brief 
 * delet element
 * @param p                     source link table
 * @param add                   delete site
 * @return SingleLinkTable* 
 */
SingleLinkTable * delElement(SingleLinkTable * p, int add){
    SingleLinkTable * temp = p;
    // traverse to the previous node of the deleted node
    for(int i = 1; i < add; i ++){
        temp = temp->next;
        if(temp->next == NULL){
            printf("the node is not exist!\n");
            return p;
        }
    }
    printf("into the delete method:\n");
    // set a pointer to the deleted node separately to prevent loss
    SingleLinkTable * del = temp->next;
    // the method to delete a node is to change te pointer field of the previous node
    temp->next = temp->next->next;
    // releade the node manually to prevent memory leakage
    free(del);
    return p;
}

/**
 * @brief 
 * find element site in link table
 * @param p 
 * @param element 
 * @return int 
 */
int selectElement(SingleLinkTable * p, int element){
    SingleLinkTable * t = p;
    int i = 1;
    while (t->next){
        t = t->next;
        if(t->elem == element){
            return i;
        }
        i ++;
    }
    return -1;
}

/**
 * @brief 
 * update element
 * @param p                     source table
 * @param add                   update site
 * @param element               new element
 * @return SingleLinkTable* 
 */
SingleLinkTable *amendElement(SingleLinkTable * p, int add, int element){
    SingleLinkTable * temp = p;
    // before traverse, temp printing to the primitive node
    temp = temp->next;
    // traverse to the node to be updated
    for(int i = 1; i < add;i ++){
        temp = temp->next;
    }
    temp->elem = element;
    return p;
}

/**
 * @brief 
 * show link table
 * @param p 
 */
void display(SingleLinkTable *p){
    // temp repointing to the head node
    SingleLinkTable* temp = p;
    // if temp pointing to the next node which not NULL, execute output word
    while (temp->next){
        temp = temp->next;
        printf("%d ", temp->elem);
    }
    printf("\n");
}


int main(){
    printf("init single link table:\n");
    SingleLinkTable *p = initSingleLink();
    display(p);

    printf("insert element 5 at site 4:\n");
    p = insertElement(p, 5, 4);
    display(p);

    printf("delete element 3: \n");
    p = delElement(p, 3);
    display(p);

    printf("find the site for element 2: \n");
    int address = selectElement(p, 2);
    if(address == -1){
        printf("not have the element;\n");
    }else{
        printf("the site is : %d\n", address);
    }

    printf("modify the element 7 for site 3:\n");
    p = amendElement(p, 3, 7);
    display(p);

    return 0;
}