题解 | #牛牛的链表添加节点#

#include <stdio.h>
#include <stdlib.h>
struct node {
    int data;
    struct node* next;
};
struct node* init_node(int data) {
    struct node* head = (struct node*)malloc(sizeof(struct node));
    head->data = data;
    head->next = NULL;
    return head;
}
void push(struct node* head, int data) {
    struct node* new_node = init_node(data);
    struct node* p = head;
    while (p->next != NULL) {
        p = p->next;
    }
    p->next = new_node;
}
// void swap(struct node* head, int x, int y) {
//     if (head->data < x || head->data < y || x == y) {
//         return;
//     }
//     struct node* p = head, *q = head;
//     for (int i = 0; i < x; i++) {
//         p = p->next;
//     }
//     for (int i = 0; i < y; i++) {
//         q = q->next;
//     }
//     int temp = p->data;
//     p->data = q->data;
//     q->data = temp;
// }
// void delete_by_data(struct node* head, int data) {
//     if (head->data == 0) {
//         return;
//     }
//     struct node* p = head;
//     while (p->next != NULL) {
//         if (p->next->data == data) {
//             struct node* q = p->next;
//             p->next = p->next->next;
//             free(q);
//             continue;
//         }
//         p = p->next;
//     }
// }
void insert_after_i(struct node* head, int i){
    if (head->data<i) {
        return;
    }
    if(head->data == i){
        push(head, i);
        return;
    }
    struct node* p = head;
    for (int j=0;j<i;j++){
        p = p->next;
    }
    struct node* new_node = init_node(i);
    new_node->next = p->next;
    p->next = new_node;
}
void print_list(struct node* head) {
    if (head->data == 0) {
        return;
    }
    struct node* p = head->next;
    while (p != NULL) {
        printf("%d ", p->data);
        p = p->next;
    }
}
int main() {
    int n, i;
    scanf("%d", &n);
    scanf("%d", &i);
    struct node* head = init_node(n);
    for (int i = 0; i < n; i++) {
        int var;
        scanf("%d", &var);
        push(head, var);
    }
    insert_after_i(head, i);
    print_list(head);
    if (head != NULL) {
        free(head);
        head = NULL;
    }
}