-每日一算 10.8 #快慢指针确定链表中间数#

/*

数据结构十六讲课后作业

独立思考了一个下午居然一遍就成功了，不可思议嘿嘿

明天再来查缺补漏，很值得回味呢

*/

#include "stdio.h"

#include "stdlib.h" 

typedef void status;

typedef int ElemType;

//定义结点类型 

typedef struct node{

int data;

struct node *next;

};

typedef struct node *Linklist;

//快慢指针确定链表中间数

status GetMidNode(Linklist L, ElemType *e){ //L为指向头结点的指针，  e为指向存放中间数空间的指针 

Linklist mid;

Linklist search;

search = L -> next;

mid = L -> next;

while(search -> next != NULL){

if (search ->next ->next != NULL){

search = search ->next -> next;

mid = mid -> next;

}

else{

search = search -> next;

}

}

*e = mid -> data;

return ;

}

//创建链表 

status InitList(Linklist *L){ //指向（指针L）的指针 

Linklist p, q;

q = *L;

for (int i = 0; i < 20; i++){

p = (Linklist) malloc(sizeof(struct node));

q -> next = p;

p -> data = rand()%100 + 1;

q = p;

}

p -> next = NULL;

return ;

} 

//链表长度 

int ListLength(Linklist L){ //L为指向头结点的指针 

int j = 0;

while (L -> next != NULL){

L = L -> next;

j++;

} 

return j;

}

//输出链表

status Getlist(Linklist L){ //L为指向头结点的指针 

while (L -> next != NULL){

L = L -> next;

printf("%d ", L -> data);

} 

return ;

} 

int main(){

int i, j, e;

char ch;

Linklist L;

L = (Linklist) malloc(sizeof(struct node));

L -> next = NULL;

j = ListLength(L);

printf("初始化L后：ListLength(L) = %d\n\n", j);

printf("1.查看链表\n");

printf("2.创建随机链表\n");

printf("3.链表长度\n");

printf("4.中间结点值\n");

printf("0.退出\n");

printf("请选择你的操作：\n");

while ((ch = getchar()) != '0'){

if (ch == '1'){

Getlist(L);

printf("\n");

}

else if (ch == '2'){

InitList(&L);

Getlist(L);

printf("\n");

}

else if (ch == '3'){

j = ListLength(L);

printf("ListLength(L) = %d\n", j);

}

else if (ch == '4'){

GetMidNode(L, &e);

printf("%d\n", e);

}

}

return 0;

}