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17_13.cpp
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17_13.cpp
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//
// 17_13.cpp
//
//
// Created by Pengyan Qin on 7/22/15.
//
//
#include <iostream>
using namespace std;
struct BiNode{
int data;
BiNode *node1, *node2;
};
struct NodePair{
BiNode *head;
BiNode *tail;
NodePair():head(nullptr), tail(nullptr){}
NodePair(BiNode *head_, BiNode *tail_):head(head_), tail(tail_){}
};
void insert(BiNode *&root, int val){
if(root == nullptr){
BiNode* ptr = new BiNode();
ptr->data = val;
ptr->node1 = nullptr;
ptr->node2 = nullptr;
root = ptr;
return;
}
if(val <= root->data)
return insert(root->node1, val);
if(val > root->data)
return insert(root->node2, val);
}
void InOrderPrint(BiNode *root){
if(root == nullptr)
return;
InOrderPrint(root->node1);
cout << root->data << " ";
InOrderPrint(root->node2);
}
// method 1: take advantage of the structure NodePair to represent the linked list
void concat(BiNode *n, BiNode *m){
n->node2 = m;
m->node1 = n;
}
NodePair convert(BiNode *root){
if(root == nullptr)
return NodePair();
NodePair part1 = convert(root->node1);
NodePair part2 = convert(root->node2);
if(part1.tail != nullptr)
concat(part1.tail, root);
if(part2.head != nullptr)
concat(root, part2.head);
return NodePair(part1.head == nullptr ? root : part1.head, part2.tail == nullptr ? root : part2.tail);
}
void print_NodePair(NodePair np){
BiNode *runner = np.head;
while(runner){
cout << runner->data << " ";
runner = runner->node2;
}
cout << endl;
}
// method 2: don't use the NodePair structure, only return BiNode
BiNode* convert1(BiNode *root){ // the structure is not bad
if(root == nullptr)
return nullptr;
BiNode* left = convert1(root->node1);
BiNode* right = convert1(root->node2);
if(left == nullptr){
if(right != nullptr){
root->node2 = right;
right->node1 = root;
}
return root;
}
else{
BiNode *tmp = left;
while(tmp->node2){
tmp = tmp->node2;
}
tmp->node2 = root;
root->node1 = tmp;
root->node2 = right;
if(right != nullptr){
right->node1 = root;
}
return left;
}
}
BiNode* convert11(BiNode *root){
if(root == nullptr)
return nullptr;
BiNode* left = convert1(root->node1);
BiNode* right = convert1(root->node2);
if(left != nullptr){
BiNode *tmp = left; // tmp is the tail of left part of linked list
while(tmp->node2){
tmp = tmp->node2;
}
concat(tmp, root);
}
if(right != nullptr)
concat(root, right);
return left == nullptr ? root : left;
}
void print_BiNode(BiNode *head){
while(head){
cout << head->data << " ";
head = head->node2;
}
cout << endl;
}
//method 3: Circular Linked List
BiNode* convert_circular(BiNode *root){
if(root == nullptr)
return nullptr;
cout << root->data << endl;
BiNode* part1 = convert_circular(root->node1);
BiNode* part3 = convert_circular(root->node2);
if(part1 == nullptr && part3 == nullptr){
root->node1 = root;
root->node2 = root;
return root;
}
BiNode *tail3 = (part3 == nullptr) ? nullptr : part3->node1;
if(part1 == nullptr){
concat(part3->node1, root);
}
else{
concat(part1->node1, root);
}
if(part3 == nullptr){
concat(root, part1);
}
else{
concat(root, part3);
}
if(part1 != nullptr && part3 != nullptr)
concat(tail3, part1);
return part1 == nullptr ? root : part1;
}
BiNode* convert2(BiNode *root){
BiNode *head = convert_circular(root);
head->node1->node2 = nullptr;
head->node1 = nullptr;
return head;
}
int main(){
int A[] = {5, 1, 6, 3, 0};
int n = 5;
BiNode *root = nullptr;
for(int i = 0; i < n; ++i)
insert(root, A[i]);
InOrderPrint(root);
cout << endl;
/*
NodePair np = convert(root);
print_NodePair(np);
*/
BiNode *head = convert2(root);
print_BiNode(head);
}