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问题:如何实现一个高效的单向链表逆序输出?
出题人:阿里巴巴出题专家:昀龙/阿里云弹性人工智能负责人
参考答案:下面是其中一种写法,也可以有不同的写法,比如递归等。供参考。
typedef struct node{
int data;
struct node* next;
node(int d):data(d), next(NULL){}}node;
void reverse(node* head)
{if(head == NULL){return;}
node* pleft = NULL;
node* pcurrent = head;
node* pright = head->next;
while(pright){
pcurrent->next = pleft;
node *ptemp = pright->next;
pright->next = pcurrent;
pleft = pcurrent;
pcurrent = pright;
pright = ptemp;
}
while(pcurrent != NULL){
cout<< pcurrent->data << "\t";
pcurrent = pcurrent->next;
}
}
class Solution<T> {public void reverse(ListNode<T> head) {if (head == null || head.next == null) {return ;}
ListNode<T> currentNode = head;
Stack<ListNode<T>> stack = new Stack<>();
while (currentNode != null) {stack.push(currentNode);
ListNode<T> tempNode = currentNode.next;
currentNode.next = null; // 断开连接
currentNode = tempNode;
}
head = stack.pop();
currentNode = head;
while (!stack.isEmpty()) {currentNode.next = stack.pop();
currentNode = currentNode.next;
}
}
}
class ListNode<T>{
T val;
public ListNode(T val) {this.val = val;}
ListNode<T> next;
}
正文完