80 lines
1.3 KiB
C++
80 lines
1.3 KiB
C++
// Description := Reverse a linkedlist in groups of size K .
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// Time and space complexity :-
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// Time Complexity = O(N) and Space Complexity = O(N)
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// Example :-
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// Input: 1->2->3->4->5->6->7->8->NULL, K = 3
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// Output: 3->2->1->6->5->4->8->7->NULL
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#include<bits/stdc++.h>
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using namespace std;
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class Node{
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public:
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int data;
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Node* next;
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};
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void push(Node* &head_ref, int new_data)
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{
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Node* new_node = new Node();
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new_node->data = new_data;
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new_node->next = head_ref;
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head_ref = new_node;
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}
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void printList(Node* node)
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{
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while (node != NULL) {
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cout << node->data << " ";
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node = node->next;
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}
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}
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Node* kReverse(Node* &head, int k) {
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// base case
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if(head == NULL) {
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return NULL;
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}
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Node* next = NULL;
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Node* curr = head;
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Node* prev = NULL;
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int count= 0;
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while( curr != NULL && count < k ) {
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next = curr -> next;
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curr -> next = prev;
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prev = curr;
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curr = next;
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count++;
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}
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if(next != NULL) {
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head -> next = kReverse(next,k);
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}
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return prev;
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}
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int main(){
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Node* head=NULL;
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Node* ans =head;
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push(head,1);
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push(head,2);
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push(head,3);
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push(head,4);
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push(head,5);
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push(head,6);
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push(head,7);
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push(head,8);
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printList(head);
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head = kReverse(head,3);
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cout<<endl;
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printList(head);
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}
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