Created
October 11, 2016 02:08
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Reversing a linked list with 1 pointer
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| #include <iostream> | |
| #include <cstdio> | |
| #include <cstdlib> | |
| #include <cmath> | |
| using namespace std; | |
| struct node { | |
| int key; | |
| node* next; | |
| node (int k) { | |
| key = k; | |
| next = NULL; | |
| } | |
| }; | |
| bool rev_head_flag = true; | |
| node* head = NULL; | |
| node* head2; | |
| void insert(int val) { | |
| node* n = new node(val); | |
| if (!head) { | |
| head = n; | |
| return; | |
| } else { | |
| node* temp = head; | |
| while (temp->next != NULL) { | |
| temp = temp -> next; | |
| } | |
| temp -> next = n; | |
| } | |
| } | |
| node*& rev(node*& p) { | |
| if (p -> next) { | |
| rev(p -> next)-> next = p; | |
| } | |
| if (rev_head_flag) { | |
| head2 = p; | |
| rev_head_flag = false; | |
| } | |
| return p; | |
| } | |
| void print_list() { | |
| node* temp = head; | |
| while (temp != NULL) { | |
| cout << "Data: "<<temp -> key << endl; | |
| temp = temp -> next; | |
| } | |
| } | |
| void print_list2() { | |
| node* temp = head2; | |
| while (temp != NULL) { | |
| cout << "Data: "<<temp -> key << endl; | |
| temp = temp -> next; | |
| } | |
| } | |
| int main() { | |
| insert(5); | |
| insert(6); | |
| insert(7); | |
| print_list(); | |
| rev(head); | |
| head -> next = NULL; | |
| print_list2(); | |
| return 0; | |
| } | |
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