tree-orders.py

# python3

import sys
import threading
sys.setrecursionlimit(10**6)  # max depth of recursion
threading.stack_size(2**27)  # new thread will get stack of such size


class TreeOrders:
    def read(self):
        self.n = int(sys.stdin.readline())
    self.key = [0 for i in range(self.n)]
    self.left = [0 for i in range(self.n)]
    self.right = [0 for i in range(self.n)]
    for i in range(self.n):
        [a, b, c] = map(int, sys.stdin.readline().split())
        self.key[i] = a
        self.left[i] = b
        self.right[i] = c

        def inOrder(self):
            self.result = []

    def inOrder_recursive(root):
        if self.left[root] != -1:
            inOrder_recursive(self.left[root])
            self.result.append(self.key[root])
            if self.right[root] != -1:
                inOrder_recursive(self.right[root])

    inOrder_recursive(0)
    return self.result


def preOrder(self):
    self.result = []

    def preOrder_recursive(root):
        self.result.append(self.key[root])
        if self.left[root] != -1:
            preOrder_recursive(self.left[root])
            if self.right[root] != -1:
                preOrder_recursive(self.right[root])

    preOrder_recursive(0)
    return self.result


def postOrder(self):
    self.result = []

    def postOrder_recursive(root):
        if self.left[root] != -1:
            postOrder_recursive(self.left[root])
            if self.right[root] != -1:
                postOrder_recursive(self.right[root])
                self.result.append(self.key[root])

    postOrder_recursive(0)
    return self.result


def main():
    tree = TreeOrders()
    tree.read()
    print(" ".join(str(x) for x in tree.inOrder()))
    print(" ".join(str(x) for x in tree.preOrder()))
    print(" ".join(str(x) for x in tree.postOrder()))


threading.Thread(target=main).start()