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1. Title Description

Reverse a single linked list. Example: input: 1 - > 2 - > 3 - > 4 - > 5 - > NULL output: 5 - > 4 - > 3 - > 1 - > 2 - > NULLCopy the code

Second, train of thought analysis

We can start by inverting two nodes in the linked list, such as:... n, n + 1, ... . n + 1, n, ... N.ext = n Reverses multiple nodes: Double Pointers traverse the list, repeating as if reversing two nodesCopy the code

Three, the solution code

/** * Definition for singly-linked list. * function ListNode(val, next) { * this.val = (val===undefined ? 0 : val) * this.next = (next===undefined ? null : next) * } */
/ * * *@param {ListNode} head
 * @return {ListNode}* /
 
 var reverseList = function(head) {
    let p1 = head;
    let p2 = null;
    while(p1) {
        const temp = p1.next
        p1.next = p2
        p2 = p1
        p1 = temp
    }
    return p2
};
 

Copy the code

Four,

  • Reversing a linked list can be started by reversing two nodes and then iterating through the operation with a double pointer.
  • Practice every day and keep learning