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

typedef struct {
 int *head;
 int length;
 int capacity;
} Toslist; //Toslist類型


//初始化順序表
Toslist initSeqlist() {
 Toslist list;
 list.length = 0;
 list.capacity = 5;
 list.head = (int *)malloc(10 * sizeof(int));

 if (!list.head)
 {
 printf("初始化失敗！\n");
 exit(0);
 }
 return list;
}

//打印順序表
void displayList(Toslist list) {
 for (int i = 0; i < list.length; i++) {
 printf("%d ", list.head[i]);
 }
 printf("\n");
}

//插入元素
Toslist add(Toslist list, int elem, int pos) {
 if (list.length == list.capacity) {
 int *temp = (int *)realloc(list.head, (list.capacity + 1) * sizeof(int));//判斷空間是否足夠，不夠就另建鏈表

//不直接用head而引入temp的作用：防止空間分配失敗導(dǎo)致head失去原來的鏈表
 if (!temp) {
  list.head = temp;
  list.capacity += 1;
 }
 }

 //插入位置及以后的元素后移

 for (int i = list.length - 1; i >= pos; i--) {
 list.head[i + 1] = list.head[i];
 }
 list.head[pos] = elem;
 list.length ++;
 return list;

 if (pos > list.length || pos < 0)
 printf("插入位置錯(cuò)誤！\n");
 return list;
}

//刪除元素
Toslist delete(Toslist list, int pos) {

 for (int i = pos; i < list.length - 1; i++) {
 list.head[i] = list.head[i + 1];
 }

 list.length--;

 return list;

 if (pos < 0 || pos > list.length) {
 printf("刪除位置有誤！\n");
 return list;
 }
}

//查
int search(Toslist list, int elem) { //elem是查找的元素
 //順序查找
 for (int i = 0; i < list.length; i++) {
 if (elem == list.head[i]) {
  return i;
 }
 }
 return 0;
}

//改
Toslist modify(Toslist list, int elem, int val) { //val是要替換它的元素
 int pos = search(list, elem); //獲取要替換元素的位置
 list.head[pos] = val;
 return list;
}

int main() {
 Toslist list = initSeqlist();
 int Addpos = -1, Addnum, Delpos, Serachnum,Modifynum;

 printf("請(qǐng)輸入5個(gè)整數(shù)元素\n");

 for (int i = 0; i < 5; i++) {
 scanf("%d", &list.head[i]);
 list.length++;
 }

 printf("順序表中的元素有：\n");
 displayList(list);

 //插入元素
 printf("要在哪個(gè)元素后插入元素？\n");
 while (Addpos < 0 || Addpos > list.length) {
 scanf("%d", &Addpos);

 if (Addpos < 0 || Addpos > list.length)
  printf("請(qǐng)輸入正確的位置！\n");
 };

 printf("請(qǐng)輸入需要插入的元素：\n"); scanf("%d", &Addnum);
 printf("在順序表的第%d個(gè)元素后插入元素%d得到\n", Addpos, Addnum);
 list = add(list, Addnum, Addpos);

 displayList(list);


 //刪除元素
 printf("要?jiǎng)h除順序表下標(biāo)順序中哪個(gè)元素？\n"); scanf("%d", &Delpos);
 printf("刪除后得到：\n");

 list = delete(list, Delpos);
 displayList(list);


 //查找
 printf("請(qǐng)輸入需要查找的元素\n"); scanf("%d", &Serachnum);

 int pos = search(list, Serachnum);
 if(pos)
 printf("元素%d的位置為第%d個(gè)\n", Serachnum, pos+1);
 if(!pos){
 printf("表中無該元素\n");
 }


 //修改
 printf("請(qǐng)輸入需要修改的元素：\n");scanf("%d",&Serachnum);
 printf("請(qǐng)輸入要替換的數(shù)：\n");scanf("%d",&Modifynum);
 printf("將%d修改為%d得到：\n", Serachnum, Modifynum);
 list = modify(list, Serachnum, Modifynum);
 displayList(list);

 free(list.head);
 list.head = NULL;

 return 0;
}