C语言双向链表类型例子

Question

有一个双向链表，将它所有的正数都加倍
比如1 2 -3 -4变为1 1 2 2 -3 -4

Answer 1

你题目的解答代码如下：

#include <stdio.h>
#include <stdlib.h>
typedef struct line{
    struct line * prior;
    int data;
    struct line * next;
}line;

line* initLine(line * head,int a[], int n);
line * insertLine(line * head,int data,int add);
line * delLine(line * head,int data);
void display(line * head);
int main() {
    int a[] = {1,2,-3,-4,5};
    line * head=NULL;
    head=initLine(head, a,5);
    display(head);
    line * temp=head;
    int i = 0;
    while (temp) {
        i++;
        if (temp->data>0)
            head=insertLine(head, temp->data,i++);
        temp=temp->next;
    }
    display(head);

    return 0;
}
line* initLine(line * head,int a[], int n){
    head=(line*)malloc(sizeof(line));
    head->prior=NULL;
    head->next=NULL;
    head->data=a[0];
    line * list=head;
    for (int i=1; i<n; i++) {
        line * body=(line*)malloc(sizeof(line));
        body->prior=NULL;
        body->next=NULL;
        body->data=a[i];

        list->next=body;
        body->prior=list;
        list=list->next;
    }
    return head;
}
line * insertLine(line * head,int data,int add){
    //新建数据域为data的结点
    line * temp=(line*)malloc(sizeof(line));
    temp->data=data;
    temp->prior=NULL;
    temp->next=NULL;
    //插入到链表头，要特殊考虑
    if (add==1) {
        temp->next=head;
        head->prior=temp;
        head=temp;
    }else{
        line * body=head;
        //找到要插入位置的前一个结点
        for (int i=1; i<add-1; i++) {
            body=body->next;
        }
        //判断条件为真，说明插入位置为链表尾
        if (body->next==NULL) {
            body->next=temp;
            temp->prior=body;
        }else{
            body->next->prior=temp;
            temp->next=body->next;
            body->next=temp;
            temp->prior=body;
        }
    }
    return head;
}

//输出链表的功能函数
void display(line * head){
    line * temp=head;
    while (temp) {
        printf("%d ",temp->data);
        temp=temp->next;
    }
    printf("\n");
}

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