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SymmetricTree.cpp
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SymmetricTree.cpp
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#include <iostream>
using namespace std;
struct TreeNode {
int val;
TreeNode *left;
TreeNode *right;
TreeNode(int x) : val(x), left(NULL), right(NULL) {}
};
bool isSym(TreeNode* left, TreeNode* right);
bool isSymmetric(TreeNode *root);
int main()
{
TreeNode *a = new TreeNode(1);
TreeNode *b = new TreeNode(2);
TreeNode *c = new TreeNode(3);
a->left = b;
a->right = c;
if(isSymmetric(a)) cout<<"is symmetric"<<endl;
else cout<<"not symmetric"<<endl;
return 1;
}
bool isSymmetric(TreeNode *root) {
if(root== NULL) return true;
return isSym(root->left,root->right);
}
bool isSym(TreeNode* left, TreeNode* right){
if(!left) return (!right);
if(!right) return (!left);
if(left->val != right->val) return false;
if(!isSym(left->left,right->right)) return false;
if(!isSym(left->right,right->left)) return false;
return true;
}