98 lines
1.7 KiB
C++
98 lines
1.7 KiB
C++
/*
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Algorithm:
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(i) Traverse the list and push all of its nodes onto a stack.
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(ii) Traverse the list from the head node again and pop a value
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from the stack top and connect them in reverse order.
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TIME COMPLEXITY: O(n), as we are traversing over the linked list of size N using a while loop.
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SPACE COMPLEXITY: o(n), as we are using stack of size N in worst case which is extra space.
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*/
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#include <iostream>
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#include <stack>
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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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Node *head;
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void Print(Node* n);
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void RevList();
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int main() {
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head = NULL;
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Node *first = new Node;
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Node *second = new Node;
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Node *third = new Node;
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Node *fourth = new Node;
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Node *fifth = new Node;
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Node *sixth = new Node;
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Node *seventh = new Node;
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head = first;
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first->data = 10;
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first->next = second;
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second->data = 20;
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second->next = third;
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third->data = 30;
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third->next = fourth;
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fourth->data = 40;
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fourth->next = fifth;
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fifth->data = 50;
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fifth->next = sixth;
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sixth->data = 60;
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sixth->next = seventh;
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seventh->data = 70;
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seventh->next = NULL;
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Print(head);
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RevList();
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cout<<endl;
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Print(head);
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return 0;
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}
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void Print(Node* n){
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if(n==NULL){
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return;
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}
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cout<<n->data<<" ";
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Print(n->next);
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}
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void RevList() {
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if(head == NULL) return;
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stack<Node *> st;
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Node * temp = head;
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while(temp!= NULL){
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st.push(temp);
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temp = temp->next;
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}
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temp = st.top();
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head = temp;
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st.pop();
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while(!st.empty()) {
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temp->next = st.top();
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temp = temp->next;
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st.pop();
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}
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temp->next = NULL;
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}
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