js 翻轉鏈表

<script>
    const obj = {
        value: 1,
        next: {
            value: 2,
            next: {
                value: 3,
                next: {
                    value: 4,
                    next: {
                        value: 5,
                        next: null
                    }
                }
            }
        }
    }

    function ReverseList(pHead) {
        if (pHead === null) {
            return null
        }
        let head = pHead;
        let last = null;

        function reverse(pNode) {

            if (pNode.next === null) {
                last = pNode;
                return pNode;
            } else {
                let node = reverse(pNode.next);
                node.next = pNode;
                if (pNode === head) {
                    pNode.next = null
                    return last;
                } else {
                    return pNode;
                }
            }
        }
        return reverse(pHead);
    }


    // let b = ReverseList(obj)
    // console.log(b);
    reverseList = function (head) {
        // debugger
        let prev = null, //  定義一個變量是null
            curr = head //  保存原始鏈表
        while (curr) { // 進入循壞
            const next = curr.next // 吧原始值next取出來   原始鏈表的next
            curr.next = prev //當前的next =prev

            prev = curr //prev 變成了{next:null}
            curr = next
        }
        return prev
    };
    let c = reverseList(obj)
    console.log(c);


    //鏈表四步走
    // 1.聲明一個pre 和curr  prev 是null， cur 是傳入的初始鏈表
    // 2.循環  循壞條件是是否存在初始鏈表
    // 3. 聲明next next 是cur的next節點
    // 4.cur的next 是prev
    // 5.prev 是cur
    // 6.cur 又等於next
</script>