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import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.*;
public class TreeTraversal {
static class FastScanner {
StringTokenizer tok = new StringTokenizer("");
BufferedReader in;
FastScanner() {
in = new BufferedReader(new InputStreamReader(System.in));
}
String next() throws IOException {
while (!tok.hasMoreElements())
tok = new StringTokenizer(in.readLine());
return tok.nextToken();
}
int nextInt() throws IOException {
return Integer.parseInt(next());
}
}
static class TreeOrders {
int n;
int[] key, left, right;
void read() throws IOException {
FastScanner in = new FastScanner();
n = in.nextInt();
key = new int[n];
left = new int[n];
right = new int[n];
for (int i = 0; i < n; i++) {
key[i] = in.nextInt();
left[i] = in.nextInt();
right[i] = in.nextInt();
}
}
List<Integer> inOrder() {
Stack<Integer> keyIndexStack = new Stack<>();
ArrayList<Integer> result = new ArrayList<>();
// Finish the implementation
// You may need to add a new recursive method to do that
boolean walkLeft = true;
int currentIndex = 0;
keyIndexStack.push(currentIndex);
while (!keyIndexStack.empty() || right[currentIndex] != -1) {
if (walkLeft) {
if (left[currentIndex] != -1) {
currentIndex = left[currentIndex];
keyIndexStack.push(currentIndex);
} else {
result.add(key[keyIndexStack.pop()]);
walkLeft = false;
}
} else {
if (right[currentIndex] != -1) {
currentIndex = right[currentIndex];
keyIndexStack.push(currentIndex);
walkLeft = true;
} else {
if (!keyIndexStack.empty()) {
currentIndex = keyIndexStack.pop();
result.add(key[currentIndex]);
}
}
}
}
return result;
}
List<Integer> preOrder() {
Stack<Integer> keyIndexStack = new Stack<>();
Queue<Integer> keyIndexQueue = new LinkedList<>();
ArrayList<Integer> result = new ArrayList<>();
// Finish the implementation
// You may need to add a new recursive method to do that
boolean walkLeft = true;
int currentIndex = 0;
keyIndexStack.push(currentIndex);
keyIndexQueue.add(currentIndex);
while (!keyIndexStack.empty() || right[currentIndex] != -1) {
if (walkLeft) {
if (left[currentIndex] != -1) {
currentIndex = left[currentIndex];
keyIndexQueue.add(currentIndex);
keyIndexStack.push(currentIndex);
} else {
keyIndexStack.pop();
walkLeft = false;
result.add(key[keyIndexQueue.remove()]);
}
} else {
if (right[currentIndex] != -1) {
currentIndex = right[currentIndex];
keyIndexQueue.add(currentIndex);
keyIndexStack.push(currentIndex);
walkLeft = true;
} else {
if (!keyIndexStack.empty()) {
currentIndex = keyIndexStack.pop();
result.add(key[keyIndexQueue.remove()]);
}
}
}
}
return result;
}
List<Integer> postOrder() {
Stack<Integer> keyIndexStack = new Stack<>();
HashSet<Integer> peekedSet = new HashSet<>();
ArrayList<Integer> result = new ArrayList<>();
// ArrayList<Integer> bothSidesHaveBeenChecked = new ArrayList<>();
// Finish the implementation
// You may need to add a new recursive method to do that
boolean walkLeft = true;
int currentIndex = 0;
keyIndexStack.push(currentIndex);
// while (!keyIndexStack.empty() || right[currentIndex] != -1) {
while (!keyIndexStack.empty()) {
if (peekedSet.contains(currentIndex)) {
result.add(key[currentIndex]);
peekedSet.remove(currentIndex);
keyIndexStack.pop();
if (keyIndexStack.empty()) break;
currentIndex = keyIndexStack.peek();
continue;
}
if (walkLeft) {
if (left[currentIndex] != -1) {
currentIndex = left[currentIndex];
keyIndexStack.push(currentIndex);
} else {
if (right[currentIndex] == -1) {
result.add(key[currentIndex]);
walkLeft = false;
keyIndexStack.pop();
currentIndex = keyIndexStack.peek();
} else {
peekedSet.add(currentIndex);
currentIndex = right[currentIndex];
keyIndexStack.push(currentIndex);
}
}
} else {
if (right[currentIndex] != -1) {
peekedSet.add(currentIndex);
currentIndex = right[currentIndex];
keyIndexStack.push(currentIndex);
walkLeft = true;
} else {
result.add(key[currentIndex]);
int i = keyIndexStack.pop();
if (i != currentIndex)
result.add(key[i]);
if (keyIndexStack.empty()) break;
currentIndex = keyIndexStack.peek();
}
}
}
return result;
}
}
static public void main(String[] args) throws IOException {
new Thread(null, new Runnable() {
public void run() {
try {
new TreeTraversal().run();
} catch (IOException ignored) {
}
}
}, "1", 1 << 26).start();
}
private void print(List<Integer> x) {
for (Integer a : x) {
System.out.print(a + " ");
}
System.out.println();
}
private void run() throws IOException {
TreeOrders tree = new TreeOrders();
tree.read();
print(tree.inOrder());
print(tree.preOrder());
print(tree.postOrder());
}
}
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