725. 分隔链表
【代码】
/**
* Definition for singly-linked list.
* function ListNode(val, next) {
* this.val = (val===undefined ? 0 : val)
* this.next = (next===undefined ? null : next)
* }
*/
/**
* @param {ListNode} head
* @param {number} k
* @return {ListNode[]}
*/
var splitListToParts = function(head, k) {
let n = 0;
let cur = head;
while (cur != null) {
n++;
cur = cur.next;
}
let p = Math.floor(n / k), q = n % k;
const parts = new Array(k).fill(null);
let curr = head;
for (let i = 0; i < k, curr != null; i++) {
parts[i] = curr;
let partSize = p + (i < q ? 1 : 0);
for (let j = 1; j < partSize; j++) {
curr = curr.next;
}
const next = curr.next;
curr.next = null;
curr = next;
}
return parts;
}
分割链表
【代码】
/**
* Definition for singly-linked list.
* function ListNode(val) {
* this.val = val;
* this.next = null;
* }
*/
/**
* @param {ListNode} head
* @param {number} x
* @return {ListNode}
*/
var partition = function(head, x) {
let cur = head
let s = new ListNode(null), s1 = s
let m = new ListNode(null), m1 = m
while(cur != null){
if(cur.val < x) {
s.next = new ListNode(cur.val)
s = s.next
}else{
m.next = new ListNode(cur.val)
m = m.next
}
cur = cur.next
}
m.next = null
s.next = m1.next
return s1.next
};
环路检测
【代码】
/**
* Definition for singly-linked list.
* function ListNode(val) {
* this.val = val;
* this.next = null;
* }
*/
/**
* @param {ListNode} head
* @return {ListNode}
*/
var detectCycle = function(head) {
if(!head || !head.next) return null
let slow = head.next, fast = head.next.next
while(fast){
if(fast !== slow){
if(!fast.next){
return null
}
slow = slow.next
fast = fast.next.next
}else{
fast = head
while(fast !== slow){
fast = fast.next
slow = slow.next
}
return fast
}
}
return null
};
删除链表的节点
【代码】
/**
* Definition for singly-linked list.
* function ListNode(val) {
* this.val = val;
* this.next = null;
* }
*/
/**
* @param {ListNode} head
* @param {number} val
* @return {ListNode}
*/
var deleteNode = function (head, val) {
if (!head) return null
if (head.val === val && !head.next) return null
let cur = head,ret = cur
while (cur && cur.next) {
let next = cur.next
if (cur.val === val) return next
if (next.val === val) {
cur.next = next.next
next.next = null
}
cur = cur.next
}
return ret
};
707. 设计链表
【代码】
// 单向链表
function ListNode(val,next) {
this.val = val;
this.next = next || null;
}
var MyLinkedList = function() {
this.size = 0
this.head = null
};
MyLinkedList.prototype.getNode = function(index) {
if (index < 0 || index >= this.size) return null
let cur = this.head
for (let i = 0; i < index; i++) {
cur = cur.next
}
return cur
};
/**
* 获取链表中第 index 个节点的值。如果索引无效，则返回-1。
* @param {number} index
* @return {number}
*/
MyLinkedList.prototype.get = function (index) {
if (index < 0 || index >= this.size) return -1
return this.getNode(index).val
};
/**
* 在链表的第一个元素之前添加一个值为 val 的节点。
* 插入后，新节点将成为链表的第一个节点。
* @param {number} val
* @return {void}
*/
MyLinkedList.prototype.addAtHead = function (val) {
let cur = this.head
let pre = new ListNode(val, cur)
this.head = pre
this.size++
};
/**
* 将值为 val 的节点追加到链表的最后一个元素。
* @param {number} val
* @return {void}
*/
MyLinkedList.prototype.addAtTail = function(val) {
if(!this.head) {
this.head = new ListNode(val)
this.size++
return
}
let newNode = new ListNode(val)
let cur = this.head
while (cur && cur.next) {
cur = cur.next
}
cur.next = newNode
this.size++
};
/**
* 在链表中的第 index 个节点之前添加值为 val 的节点。
* 如果 index等于链表的长度，则该节点将附加到链表的末尾。
* 如果 index 大于链表长度，则不会插入节点。
* 如果index小于0，则在头部插入节点。
* @param {number} index
* @param {number} val
* @return {void}
*/
MyLinkedList.prototype.addAtIndex = function (index, val) {
if (index <= 0) {
return this.addAtHead(val)
}else if (index === this.size) {
return this.addAtTail(val)
} else if(index > this.size) {
return
}
let preNode = this.getNode(index - 1)
preNode.next = new ListNode(val, preNode.next)
this.size++
};
/**
* 如果索引 index 有效，则删除链表中的第 index 个节点。
* @param {number} index
* @return {void}
*/
MyLinkedList.prototype.deleteAtIndex = function(index) {
if (index < 0 || index >= this.size) return
if (index === 0) {
this.head = this.head.next
this.size--
return
}
let indexNode = this.getNode(index)
let pre = this.getNode(index - 1)
pre.next = indexNode.next
this.size--
};
/**
* Your MyLinkedList object will be instantiated and called as such:
* var obj = new MyLinkedList()
* var param_1 = obj.get(index)
* obj.addAtHead(val)
* obj.addAtTail(val)
* obj.addAtIndex(index,val)
* obj.deleteAtIndex(index)
*/
// TODO 双向链表
