JavaScript 程序用于按给定大小对链表进行分组反转
链表是一种线性数据结构,由相互连接的节点组成。反转链表意味着更改其所有元素的顺序。按给定大小对链表进行分组反转意味着,我们得到一个数字,我们将反转前给定数量的元素,然后对于下一组,我们将反转元素。我们将看到带有实现的正确代码。
示例
Given linked list: 1 -> 2 -> 3 -> 4 -> 5 -> 6 -> 7 -> 8 -> null Given number: 3 Output: 3 -> 2 -> 1 -> 6 -> 5 -> 4 -> 8 -> 7 -> null
说明 − 在给定的链表中,我们必须将元素分组为 3-3 组,这导致三组:1、2、3 组一,我们将将其反转为 3、2 和 1。类似地,对于第二组 4、5 和 6,它将反转为 6、5 和 4。最后,最后一组不是确切的给定大小,因此我们将只取剩余的元素数量。因此,对于 7 和 8,我们将将其反转为 8 和 7。
让我们看看解决此问题的不同方法 −
示例:迭代方法
// class to create the structure of the nodes
class Node{
constructor(data){
this.value = data;
this.next = null;
}
}
// function to print the linked list
function print(head){
var temp = head;
if(head == null){
console.log("The given linked list is empty");
} else {
var ans = ""
while(temp.next != null){
ans += temp.value;
ans += " -> "
temp = temp.next
}
ans += temp.value
ans += " -> null"
}
console.log(ans)
}
// function to add data in linked list
function add(data, head, tail){
return tail.next = new Node(data);
}
// function to remove the duplicate numbers
function reverseGroup(head, number){
if (!head || number == 1){
return head;
}
var temp = new Node();
temp.value = -1;
temp.next = head;
var prev = temp;
var cur = temp;
var next = temp;
// Calculating the length of linked list
var len = 0;
while (cur) {
len++;
cur = cur.next;
}
// Iterating till next is not NULL
while (next) {
cur = prev.next;
next = cur.next;
var toL = len > number ? number : len - 1;
for (var i = 1; i < toL; i++) {
cur.next = next.next;
next.next = prev.next;
prev.next = next;
next = cur.next;
}
prev = cur;
len -= number;
}
return temp.next;
}
// defining linked list
var head = new Node(1)
var tail = head
tail = add(2,head, tail)
tail = add(3,head, tail)
tail = add(4,head, tail)
tail = add(5,head, tail)
tail = add(6,head, tail)
tail = add(7,head, tail)
tail = add(8,head, tail)
// given number
var number = 3
console.log("The given linked list is: ")
print(head)
// calling function to reverse elements in group
head = reverseGroup(head,number)
console.log("The Linked list after reversing elements in groups of 3 is: ")
print(head)
示例:递归方法
在这种方法中,我们将使用递归的概念,让我们看看代码 −
// class to create the structure of the nodes
class Node{
constructor(data){
this.value = data;
this.next = null;
}
}
// function to print the linked list
function print(head){
var temp = head;
if(head == null){
console.log("The given linked list is empty");
}
else{
var ans = ""
while(temp.next != null){
ans += temp.value;
ans += " -> "
temp = temp.next
}
ans += temp.value
ans += " -> null"
}
console.log(ans)
}
// function to add data in linked list
function add(data, head, tail){
return tail.next = new Node(data);
}
// function to remove the duplicate numbers
function reverseGroup(head, number){
if (head == null){
return null;
}
var cur = head;
var next = null;
var prev = null;
var cnt = 0;
while (cnt < number && cur != null){
next = cur.next;
cur.next = prev;
prev = cur;
cur = next;
cnt++;
}
if (next != null){
head.next = reverseGroup(next, number);
}
return prev;
}
// defining linked list
var head = new Node(1)
var tail = head
tail = add(2,head, tail)
tail = add(3,head, tail)
tail = add(4,head, tail)
tail = add(5,head, tail)
tail = add(6,head, tail)
tail = add(7,head, tail)
tail = add(8,head, tail)
// given number
var number = 3
console.log("The given linked list is: ")
print(head)
// calling function to reverse elements in group
head = reverseGroup(head,number)
console.log("The Linked list after reversing elements in groups of 3 elements is: ")
print(head)
结论
在本教程中,我们实现了 JavaScript 程序来旋转给定链表中给定长度的子组。我们实现了两种方法;一种是递归的,另一种是迭代的。两种方法都可以在 O(N) 时间复杂度内工作。
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