Print Boundry Nodes of a binary tree.

void printLeaves(TreeNode* root) {
if(root) {
printLeaves(root->left);
if(!(root->left) && !(root->right)) cout << root->val << endl;
printLeaves(root->right);
}
}

void PrintBoundryRight(TreeNode* root) {
if(root) {
if(root->right) {
PrintBoundryRight(root->right);
cout << root->val << endl;
} else if(root->left) {
PrintBoundryRight(root->left);
cout << root->val << endl;
}
}
}

void PrintBoundryLeft(TreeNode* root) {
if(root) {
if(root->left) {
cout << root->val << endl;
PrintBoundryLeft(root->left);
} else if(root->right) {
cout << root->val << endl;
PrintBoundryLeft(root->right);
}
}
}

void printBoundry(TreeNode* root) {
if(!root) return;
cout << root->val << endl;
PrintBoundryLeft(root->left);

printLeaves(root->left);
printLeaves(root->right);

PrintBoundryRight(root->right);
}