/**
* @param root: a TreeNode
* @return: a list of integer
*/
void find_leaves(TreeNode *root, vector<int> &leaves)
{
if(!root)
return;
find_leaves(root->left, leaves);
if(root->left == NULL && root->right == NULL)
leaves.push_back(root->val);
find_leaves(root->right, leaves);
}
void find_leaves(node_t root, int* count)
{
if(root != NULL)
{
find_leaves(root -> rlink, count);
if(root -> llink == NULL && root -> rlink == NULL)
{
*count = *count + 1;
}
find_leaves(root -> llink, count);
}
}
vector<int> boundaryOfBinaryTree(TreeNode * root) {
// write your code here
if(!root)
return {};
else if(root->left == NULL && root->right == NULL)
return {root->val};
vector<int> ans;
ans.push_back(root->val);
TreeNode* node;
// Find left boundary
node = root->left;
vector<int> left_boundary;
find_left_most(node, left_boundary);
// Find all leaves
vector<int> leaves;
find_leaves(root, leaves);
// Find right boundary, reverse it
node = root->right;
vector<int> right_boundary;
find_right_most(node, right_boundary);
reverse(right_boundary.begin(), right_boundary.end());
for(auto x: left_boundary)
ans.push_back(x);
for(auto x: leaves)
ans.push_back(x);
for(auto x: right_boundary)
ans.push_back(x);
return ans;
}