Add solution for Issue #77: Symmetric Trees

C++/Issue77SymmetricTrees.cpp

@@ -0,0 +1,70 @@
+#include <iostream>
+#include <queue>
+using namespace std;
+
+// Definition of TreeNode
+struct TreeNode {
+    int val;
+    TreeNode* left;
+    TreeNode* right;
+
+    TreeNode(int x) {
+        val = x;
+        left = right = NULL;
+    }
+};
+
+bool isSymmetric(TreeNode* root) {
+    if (root == NULL) return true;
+
+    queue<TreeNode*> q;
+
+    // Push left and right children of root
+    q.push(root->left);
+    q.push(root->right);
+
+    while (!q.empty()) {
+        TreeNode *leftNode=q.front();
+        q.pop();
+        TreeNode *rightNode=q.front();
+        q.pop();
+        if(leftNode==NULL && rightNode!=NULL) {
+            return false;
+        }
+        else if(leftNode!=NULL && rightNode==NULL) {
+            return false;
+        }
+        else if(leftNode!=NULL && rightNode!=NULL) {
+            if(leftNode->val!=rightNode->val) {
+                return false;
+            }
+        }
+        if(leftNode->left!=NULL) {
+            q.push(leftNode->left);
+        }
+        if(rightNode->right!=NULL) {
+            q.push(rightNode->right);
+        }
+        if(leftNode->right!=NULL) {
+            q.push(leftNode->right);
+        }
+        if(rightNode->left!=NULL) {
+            q.push(rightNode->left);
+        }
+    }
+
+    return true;
+}
+
+int main() {
+    TreeNode *root=new TreeNode(1);
+    root->left=new TreeNode(2);
+    root->left->left=new TreeNode(3);
+    root->left->right=new TreeNode(4);
+    root->right=new TreeNode(2);
+    root->right->left=new TreeNode(4);
+    root->right->right=new TreeNode(3);
+
+    cout << isSymmetric(root);
+    return 0;
+}