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IsSymmetry.cpp
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IsSymmetry.cpp
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#include<iostream>
#include<queue>
using namespace std;
class Node{
public:
int data;
Node* left;
Node* right;
Node(int data)
{
data = data;
left = NULL;
right = NULL;
}
};
void printBT(const std::string& prefix, const Node* node, bool isLeft)
{
if (node != nullptr)
{
std::cout << prefix;
std::cout << (isLeft ? "|--" : "L--");
std::cout << node->data << std::endl;
printBT(prefix + (isLeft ? "| " : " "), node->right, true);
printBT(prefix + (isLeft ? "| " : " "), node->left, false);
}
}
void printBT(const Node* node)
{
printBT("", node, false);
}
/*
Binary Tree is symmetrical if it is a mirror image
Leetcode: 101.
*/
//iterative solution
bool isSymmetric(Node* root) {
Node* curr = root;
queue<Node*> q;
q.push(root->left);
q.push(root->right);
while(!q.empty())
{
Node* l = q.front();
q.pop();
Node* r = q.front();
q.pop();
if(!l && !r)
continue;
if(!l || !r)
return false;
if(l->data!=r->data)
return false;
q.push(l->left);
q.push(r->right);
q.push(l->right);
q.push(r->left);
}
return true;
}
// Recursive
bool helper(Node* lt, Node* rt)
{
if(lt==NULL && rt==NULL)
return true;
if(lt==NULL || rt==NULL)
return false;
return helper(lt->left, rt->right) && helper(lt->right, rt->left);
}
bool isSymmetricRecursive(Node* root)
{
return helper(root->left, root->right);
}
int main()
{
Node* root = new Node(1);
root->left = new Node(2);
root->right = new Node(3);
return 0;
}