常见的链表操作

链表操作是算法基本功之一，最近看算法，做了几个链表比较基础的题目。大家看这些题目，拿着纸笔画一画，思路瞬间清晰。之后希望持续更新~~。

        //定义链表
        function Node (value) {
            this.value = value;
            this.next = null;
        }
        //把数组转化成链表
        function arrToList (arr) {
            var head = new Node(arr[0]);
            var node = head
            for(var i=1; i < arr.length; i++) {
                var onode = new Node(arr[i]);
                node.next = onode;
                node = node.next;
            }
            return head;
        }
        //获取链表长度
        function getLength (list) {
            var length = 0;
            while (list != null) {
                list = list.next;
                length = length + 1;
            }
            return length;
        }

        //算法1：翻转链表
        function reverseList (head) {
            var p = null;
            while (head!=null) {
                var q = head.next;
                head.next = p;
                p = head; 
                head = q;
                console.log(q);
            }
            return p;
        }

        //算法2: 判断链表是否有环
        function hasCircle (head) {
            if(head == null || head.next == null) {
                return false;
            }
            var fast = head.next;
            var slow = head;
            while (fast != slow) {
                if (fast == null || fast.next == null) {
                    return false;
                }
                fast = fast.next.next;
                slow =slow.next;
            }
            return true;
        }

        /*var list1 = arrToList([1,2,3,4,5,6,7]);
        var list2 = arrToList([8,9,10]);
        var list3 =list.next;
        list.next.next = list2;
        list2.next.next.next = list3;*/


        //算法3: 链表相加求和
        function addList (list1,list2) {
            var carry = 0;
            var head = new Node(0);
            var point = head;
            while (list1!=null && list2!=null) {
                //num,carry的取值是重点
                var num = (list1.value + list2.value + carry);
                point.next =  new Node(num % 10);
                carry = parseInt(num/10);
                list1 = list1.next;
                list2 = list2.next;
                point = point.next;
            }
            while (list1!=null) {
                var num = (list1.value + carry);
                point.next =  new Node(num % 10);
                carry = parseInt(num/10);
                list1 = list1.next;
                point = point.next;
            }
            while (list2!=null) {
                var num = (list2.value + carry);
                point.next =  new Node(num % 10);
                carry = parseInt(num/10);
                list2 = list2.next;
                point = point.next;
            }
            while (carry !=0) {
                var num = carry;
                point.next =  new Node(num % 10);
                carry = parseInt(num/10);
            }
            return head;
        }

        //算法4: 删除链表倒数第n个节点
        function deleteKpoint (list,k) {
            var p = list;
            var q = list;
            while (k > 0) {
                if (list == null) {
                    return null;
                }
                list = list.next;
                k = k-1;
            }
            //注意这里的临界值判断
            while (list.next != null) {
                p = p.next;
                list = list.next;
            }
            p.next = p.next.next;
            return q;
        }

        //算法5: 得到链表的倒数第n个结点
        function getKpoint (list,k) {
            var p = list;
            while (k > 0) {
                if (list == null) {
                    return null;
                }
                list = list.next;
                k = k-1;
            }
            //注意这里的临界值判断
            while (list != null) {
                p = p.next;
                list = list.next;
            }
            return p;
        }

        //算法6: 删除链表中重复的元素
        function deleteRepeat (list) {
            var p = list;
            while (list.next != null) {
                if (list.value == list.next.value) {
                    list.next = list.next.next;
                } else {
                    list = list.next;
                }
            }
            return p;
        }

        //算法7: 删除链表中重复元素,并删除该结点
        function deleteRepeat2 (list) {
            var oNode = new Node();
            oNode.next = list;
            list = oNode;
            //下面的if判断谁的value，上面的限制条件临界值就是这个
            while (list.next!=null && list.next.next!= null) {
                if (list.next.value == list.next.next.value) {
                    var number = list.next.value;
                    while (list.next != null && list.next.value == number) {
                        list.next = list.next.next;
                    }
                } else {
                    list = list.next;
                }
            }
            return oNode.next;
        }

        //算法8: 旋转链表
        function rotateList(list,k) {
            var length = getLength(list);
            k = k % length;
            var p = list;
            var q = list;
            while (list.next != null && k > 0) {
                list = list.next;
                k = k - 1;
            }
            while (list.next != null) {
                list = list.next;
                p = p.next;
            }
            var r = p.next;
            list.next = q;
            p.next = null;
            return r;
        }