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#ifdef LOCAL
#include <bits/stdc++.h>
using namespace std;
// tree node stuff here...
struct TreeNode {
int val;
TreeNode *left;
TreeNode *right;
TreeNode(int x) : val(x), left(NULL), right(NULL) {}
};
#endif
static int __initialSetup = []()
{
std::ios::sync_with_stdio(false);
cin.tie(NULL);
return 0;
}
();
class BSTIterator
{
private:
TreeNode *root;
stack<TreeNode *> st;
public:
BSTIterator(TreeNode *_root)
{
root = _root;
for (TreeNode *cur = _root; cur != NULL; cur = cur->left)
st.push(cur);
// cout << st.size() << endl;
}
/** @return whether we have a next smallest number */
bool hasNext()
{
return st.size() > 0;
}
/** @return the next smallest number */
int next()
{
TreeNode *ans = st.top();
st.pop(); // pop self! This is crucial!
for (TreeNode *cur = ans->right; cur != NULL; cur = cur->left) {
st.push(cur);
}
return ans->val;
}
};
/**
* Your BSTIterator will be called like this:
* BSTIterator i = BSTIterator(root);
* while (i.hasNext()) cout << i.next();
*/
#ifdef LOCAL
void trimLeftTrailingSpaces(string &input)
{
input.erase(input.begin(), find_if(input.begin(), input.end(),
[](int ch) {
return !isspace(ch);
}));
}
void trimRightTrailingSpaces(string &input)
{
input.erase(
find_if(input.rbegin(), input.rend(), [](int ch) {
return !isspace(ch);
})
.base(),
input.end());
}
TreeNode *stringToTreeNode(string input)
{
trimLeftTrailingSpaces(input);
trimRightTrailingSpaces(input);
input = input.substr(1, input.length() - 2);
if (!input.size()) {
return nullptr;
}
string item;
stringstream ss;
ss.str(input);
getline(ss, item, ',');
TreeNode *root = new TreeNode(stoi(item));
queue<TreeNode *> nodeQueue;
nodeQueue.push(root);
while (true) {
TreeNode *node = nodeQueue.front();
nodeQueue.pop();
if (!getline(ss, item, ',')) {
break;
}
trimLeftTrailingSpaces(item);
if (item != "null") {
int leftNumber = stoi(item);
node->left = new TreeNode(leftNumber);
nodeQueue.push(node->left);
}
if (!getline(ss, item, ',')) {
break;
}
trimLeftTrailingSpaces(item);
if (item != "null") {
int rightNumber = stoi(item);
node->right = new TreeNode(rightNumber);
nodeQueue.push(node->right);
}
}
return root;
}
string integerVectorToString(vector<int> list, int length = -1)
{
if (length == -1) {
length = list.size();
}
if (length == 0) {
return "[]";
}
string result;
for (int index = 0; index < length; index++) {
int number = list[index];
result += to_string(number) + ", ";
}
return "[" + result.substr(0, result.length() - 2) + "]";
}
int main()
{
string line;
while (getline(cin, line)) {
TreeNode *root = stringToTreeNode(line);
BSTIterator it(root);
vector<int> ret;
while (it.hasNext())
ret.push_back(it.next());
string out = integerVectorToString(ret);
cout << out << endl;
}
return 0;
}
#endif
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