C++面试常见问题——04链表的逆序与合并

链表的逆序与合并

链表的逆序

已知一个链表的头指针为head，将该链表逆序。

#include<iostream>
using namespace std;
struct Node{
    int data;
    Node* next;
};
typedef struct Node Node;
Node* ReverseLinkList(Node* head){
    Node* p1 = head;
    Node* p2 = p1->next;
    Node* p3 = p2->next;
    p1->next = NULL;
    if(p3->next != NULL){
        p2->next = p1;
        p1 = p2;
        p2 = p3;
        p3 = p3->next;
    }
    p2->next = p1;
    head =p2;
    return p2;
}
int main(){

}

有序链表的合成

已知两个链表head1，head2各自有序，合并为一个新的有序链表

#include<iostream>
using namespace std;
struct Node{
    int data;
    Node* next;
};
typedef struct Node Node;
Node* MergeLinkList(Node* head1,Node* head2){
    if(head1 == NULL){
        return head2;
    }
    if(head2 ==NULL){
        return head1;
    }
    Node* head;				//新链表
    Node* p1;				//两个辅助结点
    Node* p2;
    if(head1->data <= head2->data){			//先确定新链表的头结点
        head = head1;
        p1 = head1->next;
        p2 = head2;
    }
    else{
        head = head2;
        p1 = head1;
        p2 = head2->next;
    }
    Node* pcur = head;				//辅助结点，用来确定新加入结点
    while((p1 != NULL) && (p2 != NULL)){	//两个链表都不为空时
        if(p1->data <= p2->data){
            pcur->next = p1;
            pcur = p1;
            p1 = p1->next;
        }
        else{
            pcur->next = p2;
            pcur = p2;
            p2 = p2->next;
        }
    }
    if(p1 == NULL){
        pcur->next = p2;
    }
    else{
        pcur->next = p1;
    }
    return head;
}
int main(){

}