题解 | 牛牛的单链表求和

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

// write your code here......
//定义链表结构体
typedef struct Node{
    int data;
    struct Node* next;
}Node;

//功能：根据一个整数数组创建一个链表
//参数:arr-输入的数组;n-数组的长度
//返回值：创建好的链表的头指针
Node* createListFromArray(int* arr,int n)
{
    if(n==0)
    {
        return NULL;
    }
    Node* head = NULL;
    Node* tail = NULL;
    for(int i =0;i<n;i++)    
{
    Node* newnode = (Node*)malloc(sizeof(Node));
    newnode->data=arr[i];
    newnode->next=NULL;
    if(head==NULL)
    {
        head=newnode;
        tail=newnode;
    }else
    {
        tail->next=newnode;
        tail = newnode;
    }
}
    return head;
}

//功能:遍历链表并计算所有节点值的和
//参数:head 
//返回值：节点值的总和
int sumList(Node* head)
{
    int sum = 0;
    Node* current = head;
    while(current!= NULL)
    {
        sum=sum+current->data;
        current=current->next;
    }
    return sum;
}
//功能:释放整个链表占用的内存
//参数: head_ref - 指向头指针的指针，用于在函数内修改原始头指针
void freelist(Node** head_ref)
{
    Node* current = *head_ref;
    Node* next_node;
    while(current!=NULL)
    {
        next_node=current->next;
        free(current);
        current=next_node;
    }
        *head_ref = NULL;
}
int main() {

    int n;
    scanf("%d",&n);

    int* arr=(int*)malloc(n*sizeof(int));

    for (int i = 0; i < n; i++) {
        scanf("%d",&arr[i]);
    }
    // write your code here......
    //1.根据数组创建链表
    Node* head = createListFromArray(arr, n);
    //2.遍历链表并求和
    int totalSum = sumList(head);
    //3.打印总和
    printf("%d\n",totalSum);
    free(arr);//释放数组
    freelist(&head);
    return 0;//释放链表
}

我发现无论是链表求和还是释放链表，里面的判定条件都会有while(current!=NULL)