74. 연결 리스트의 앞쪽 삽입과 노드 삭제

1#include <stdio.h>
2#include <stdlib.h>
3 
4struct Node {
5    int val;
6    struct Node *next;
7};
8 
9void push(struct Node **head, int v) {
10    struct Node *n = (struct Node *)malloc(sizeof(struct Node));
11    n->val = v;
12    n->next = *head;
13    *head = n;
14}
15 
16int show(struct Node *p) {
17    int sum = 0;
18    while (p != NULL) {
19        printf("%d", p->val);
20        sum += p->val;
21        p = p->next;
22        printf(p != NULL ? "->" : "\n");
23    }
24    return sum;
25}
26 
27int main() {
28    int data[4] = {4, 7, 2, 9};
29    struct Node *head = NULL;
30    for (int i = 0; i < 4; i++) {
31        push(&head, data[i]);
32    }
33    int s1 = show(head);
34    struct Node *del = head->next;
35    head->next = del->next;
36    free(del);
37    int s2 = show(head);
38    printf("%d %d\n", s1, s2);
39    while (head != NULL) {
40        struct Node *t = head;
41        head = head->next;
42        free(t);
43    }
44    return 0;
45}