基础链表算法
作者：互联网
1 class NodeMake{
2 constructor(){
3 this.value=null;
4 this.next=null;
5 }
6 }
7 //随机指针节点
8 class NodeMakeRandom{
9 constructor(){
10 this.value=null;
11 this.next=null;
12 this.random=null;
13 }
14 Clone(Node){
15 this.value=Node.value;
16 this.next=Node.next;
17 this.random=Node.random;
18 }
19 }
20 function MakeLink(){
21 let head=new NodeMake();
22 for(let i=0;i<=5;i++){
23 let tmpval= Math.floor(Math.random()*10);
24 let p= new NodeMake();
25 p.value=tmpval;
26 p.next=head.next;
27 head.next=p;
28 }
29
30 return head.next;
31 }
32
33 function output(head){
34 let p=head;
35 while(p){
36 console.log(p.value);
37 p=p.next;
38 }
39 }
40 //用头插法实现反转链表
41 function ReverseLink(head){
42 if(head.next==null){
43 return head;
44 }
45 let new_head=new NodeMake();
46 let p=head;
47 while(p){
48 let tmp=p.next;
49 p.next=new_head.next
50 new_head.next=p;
51 p=tmp;
52 }
53 return new_head.next;
54
55 }
56 //判断回文，用压栈方式快速解决
57 function JudegePal1(head){
58 let stack =new Array();
59 let p=head;
60 while(p){
61 if(p.value==stack[0]){
62 stack.shift();
63 }
64 else{
65 stack.unshift(p.value);
66 }
67 p=p.next;
68 }
69 if(stack.length==0||stack.length==1){
70 console.log("是回文");
71 }
72 else{
73 console.log("不是回文");
74 }
75
76 }
77 //判断回文，用快慢指针减少空间复杂度
78 function JudegePal2(head){
79 let slow=head;
80 let fast=head;
81 while(fast&&fast.next){
82 slow=slow.next;
83 fast=fast.next.next;
84 }
85 //若链表只有一个值时返回
86 if(fast==head){
87 console.log("是回文");
88 return;
89 }
90 //从slow节点反转链表，从首尾逼近比较
91 let Tail=ReverseLink(slow);
92 let FromTail=Tail;
93 let FromHead=head;
94 let flag=1;
95 while(FromHead&&FromTail){
96 if(FromHead.value!=FromTail.value){
97 flag=0;
98 break;
99 }
100 FromHead=FromHead.next;
101 FromTail=FromTail.next;
102 }
103 ReverseLink(Tail);
104 if(flag){
105 console.log("是回文");
106 }
107 else{
108 console.log("不是回文");
109 }
110
111
112 }
113 //单链表的荷兰国旗问题
114 //用数组快速解决
115 function LessEqualMore1(head,num){
116 let arr=new Array();
117 let p=head;
118 while(p){
119 arr.push(p);
120 p=p.next;
121 }
122 GuoQi(arr,num);
123 head=arr[0];
124 let i;
125 for(i=0;i<=arr.length-2;i++){
126 arr[i].next=arr[i+1];
127 }
128 arr[i].next=null;
129 }
130 function GuoQi(arr,num){
131 let less,more,i;
132 less=-1;more=arr.length;i=0;
133 while(i<more){
134 if(arr[i].value<num){
135 less++;
136 swap(arr,i,less);
137 i++;
138 }
139 else if(arr[i].value>num){
140 more--;
141 swap(arr,i,more);
142 }
143 else{
144 i++;
145 }
146 }
147 }
148 function swap(arr,p1,p2){
149 [arr[p1],arr[p2]]=[arr[p2],arr[p1]];
150 }
151 //用六个变量标志各个区域头尾，减少空间复杂度
152 function LessEqualMore2(head,num){
153 let LessStart,LessEnd,EqualStart,EqualEnd,MoreStart,MoreEnd;
154 let p=head;
155 let new_head;
156 while(p){
157 if(p.value<num){
158 let tmp=p;
159 p=p.next;
160 if(LessStart==null){
161 LessStart=tmp;
162 LessEnd=tmp;
163 LessEnd.next=null;
164 continue;
165 }
166 let sign=LessEnd;
167 LessEnd=tmp;
168 sign.next=LessEnd;
169 LessEnd.next=null;
170 }
171 else if(p.value>num){
172 let tmp=p;
173 p=p.next;
174 if(MoreStart==null){
175 MoreStart=tmp;
176 MoreEnd=tmp;
177 MoreEnd.next=null;
178 continue;
179 }
180 let sign=MoreEnd;
181 MoreEnd=tmp;
182 sign.next=MoreEnd;
183 MoreEnd.next=null;
184 }
185 else{
186 let tmp=p;
187 p=p.next;
188 if(EqualStart==null){
189 EqualStart=tmp;
190 EqualEnd=tmp;
191 EqualEnd.next=null;
192 continue;
193 }
194 let sign =EqualEnd;
195 EqualEnd=tmp;
196 sign.next=EqualEnd;
197 EqualEnd.next=null;
198 }
199
200 }
201 if(LessStart){
202 if(EqualStart){
203 LessEnd.next=EqualStart;
204 EqualEnd.next=MoreStart;
205 }
206 else{
207 LessEnd.next=MoreStart;
208 }
209 new_head=LessStart;
210 }
211 else if(EqualStart){
212 EqualEnd.next=MoreStart;
213 new_head=EqualStart;
214 }
215 else{
216 new_head=MoreStart;
217 }
218 return new_head;
219 }
220 //随即指针链表的复制
221 //用哈希表快速解决
222 function CopyLink1(head){
223 let p=head;
224 let HashMap=new Map();
225 while(p){
226 let clone=p;
227 HashMap.set(p,clone);
228 p=p.next;
229 }
230 p=head;
231 while(p){
232 let clone=HashMap.get(p);
233 clone.next=HashMap.get(p.next);
234 clone.random=HashMap.get(p.random);
235 p=p.next;
236 }
237 return HashMap.get(head);
238 }
239 //用克隆节点直接挂节省空间
240 function CopyLink2(head){
241 let p=head;
242 while(p){
243 let sign=p;
244 p=p.next;
245 let clone=new NodeMakeRandom;
246 clone.Clone(sign);
247 sign.next=clone;
248 clone.next=p;
249 }
250 p=head;
251 let new_head;
252 new_head=p.next;
253 let tmp=new_head;
254 while(p){
255 let sign=p;
256 p=p.next.next;
257 if(tmp.random){
258 tmp.random=tmp.random.next;
259 }
260 if(p){
261 tmp.next=p.next;
262 tmp=tmp.next;
263 }
264 sign.next=p;
265 }
266 return new_head;
267
268 }
269 //判断两个有可能有环的单链表是否相交
270 function JudgeIntersect(head1,head2){
271 let loop1,loop2;
272 loop1=JudgeLoop(head1);loop2=JudgeLoop(head2);
273 //一个有环一个无环的单链表是不可能有交点的
274 if((loop1==null&&loop2!=null)||(loop1!=null&&loop2==null)){
275 console.log("没有交点");
276 return;
277 }
278 else if(loop1==null&&loop2==null){//两个无环的单链表
279 let end1,end2,length;
280 end1=head1;end2=head2;length=0;
281 while(end1.next){
282 end1=end1.next;
283 length++;
284 }
285 while(end2.next){
286 end2=end2.next;
287 length--;
288 }
289 if(end1!=end2){//终点不同的两个单链表是不会有交点的
290 console.log("没有交点");
291 return;
292 }
293 else{
294 let cur1=length>=0?head1:head2;//cur1存放长的那个链表
295 let cur2=cur1==head1?head2:head1;
296 length=Math.abs(length);
297 for(let i=1;i<=length;i++){
298 cur1=cur1.next;
299 }
300 while(cur1!=cur2){
301 cur1=cur1.next;
302 cur2=cur2.next;
303 }
304 console.log("交点是"+cur1.value);
305 return ;
306 }
307 }
308 else{//两个有环的单链表
309 if(loop1==loop2){//环的第一个点相同，相当于两个无环单链表
310 let end1,end2,length;
311 end1=head1;end2=head2;
312 while(end1!=loop1.next){
313 end1=end1.next;
314 length++;
315 }
316 while(end2!=loop1.next){
317 end2=end2.next;
318 length--;
319 }
320 let cur1=length>=0?head1:head2;//cur1存放长的那个链表
321 let cur2=cur1==head1?head2:head1;
322 length=Math.abs(length);
323 for(let i=1;i<=length;i++){
324 cur1=cur1.next;
325 }
326 while(cur1!=cur2){
327 cur1=cur1.next;
328 cur2=cur2.next;
329 }
330 console.log("交点是"+cur1.value);
331 return
332 }
333 else{//快慢指针判断交点不同的情况
334 let time=0;
335 let slow,fsat;
336 slow=loop1.next;fast=loop2.next.next;
337 while(slow!=fast){
338 if(fast==loop2||fast.next==loop2){
339 time++;
340 }
341 if(time>=3){
342 console.log("没有交点");
343 return;
344 }
345 slow=slow.next;fast=fast.next.next;
346 }
347 console.log("两个交点"+loop1.value+loop2.value);
348 return;
349 }
350
351 }
352
353 }
354 //快慢指针判断单链表有无环
355 function JudgeLoop(head){
356 if(head.next==null){
357 return null;
358 }
359 let slow,fast;
360 slow=head.next;fast=head.next.next;
361 while(slow!=fast){
362 slow=slow.next;
363 if(fast&&fast.next){
364 fast=fast.next.next;
365 }
366 else{
367 console.log("无环");
368 return null;
369 }
370 }
371 fast=head;
372 while(slow!=fast){
373 slow=slow.next;
374 fast=fast.next;
375 }
376 console.log("环的第一个点是"+slow.value);
377 return slow;
378 }
379
380 //一些测试数据
381 let head1=MakeLink();
382 let head2=MakeLink();
383 //output(head);
384 // JudegePal2(head);
385 //LessEqualMore1(head,2);
386 // output(head);
387 // console.log("*************");
388 // // JudegePal1(head);
389 // head=LessEqualMore2(head,2);
390 // head.random=head.next.next;
391 // console.log("*************");
392 // head = CopyLink2(head);
393 // output(head);
394 // output(head.random);
395 // output(head1);
396 // console.log("*************");
397 // output(head2);
398 head1.next.next.next.next=head2.next;
399 head2.next.next.next.next=head1.next;
400 // output(head1);
401 // console.log("*************");
402 // output(head2);
403 JudgeIntersect(head1,head2);
标签：tmp,head,head1,基础,next,链表,算法,let,null 来源： https://www.cnblogs.com/ZZY22110/p/16093837.html