用链表插入

 

#include<stdio.h>
#include<stdlib.h>
struct node {
	int data;
	struct node* next;//声明一个结构体
};
int main() {
	struct node * head, * p, * q=NULL, * t;//不同含义的结点
	int i, n, a;
	scanf("%d", &n);
	head = NULL;
	for (i = 0; i < n; i++) {
		scanf("%d", &a);
		p = (struct node*)malloc(sizeof(struct node));//结构体指针(动态申请一个空间，用来存放一个结点，并用临时指针p只想这个结点)
		p->data = a;
		p->next = NULL;
		if (head == NULL) {
			head = p;
		}
		else
			q->next = p;
		q = p;
	}
		scanf("%d", &a);
		t = head;//因为不能改变头结点所以要用一个临时变量t从头开始遍历
		while (t != NULL) {
			if (t->next->data > a) {
				p = (struct node*)malloc(sizeof(struct node));
				p->data= a;
				p->next = t->next;//有值有指针
				t->next = p;
				break;
			}
			t = t->next;
		}

		t = head;//
		while (t != NULL) {
			printf("%d ", t->data);
			t = t->next;
	}
		t = head;
    while (t != NULL) {
        p = t;
        t = t->next;
        free(p);
    }
	return 0;
}

ps：

1.

所以为了避免这个情况，我们要*q=NULL，

2.