Algorithms: Tree Algorithms Tutorials and Code Examples - Page 5

Iterative Binary Tree Inorder in PHP

Inorder traversal visits each binary-tree node once without recursion..

php

function tree_inorder(array $left_child, array $right_child, int $root, array &$output): int {
    alg_require(array_is_list($left_child));
    alg_require(array_is_list($right_child));
    alg_require(array_is_list($output));
    $n = count($left_child);
    alg_require((($n >= 0) && ($n <= 1000000)));
    alg_require((count($left_child) == $n));
    alg_require((count($right_child) == $n));
    alg_require((count($output) == $n));
    alg_require((($root >= alg_sub(0, 1)) && ($root < $n)));
    for ($alg_i = 0; $alg_i < count($left_child); $alg_i++) {
        $alg_value = $left_child[$alg_i];

Nov 15, 2026 PHP

Algorithms: Tree Algorithms

Iterative Binary Tree Preorder in Java

Preorder traversal visits each binary-tree node once without recursion..

java

    static int tree_preorder(int[] left_child, int[] right_child, int root, int[] output) {
        java.util.Objects.requireNonNull(left_child, "left_child");
        java.util.Objects.requireNonNull(right_child, "right_child");
        java.util.Objects.requireNonNull(output, "output");
        int n = left_child.length;
        alg_require(((n >= 0) && (n <= 1000000)));
        alg_require((left_child.length == n));
        alg_require((right_child.length == n));
        alg_require((output.length == n));
        alg_require(((root >= Math.negateExact(1)) && (root < n)));
        for (int alg_i = 0; alg_i < left_child.length; alg_i++) {
            int alg_value = left_child[alg_i];

Nov 15, 2026 Java

Algorithms: Tree Algorithms

Iterative Binary Tree Preorder in JavaScript

Preorder traversal visits each binary-tree node once without recursion..

javascript

function tree_preorder(left_child, right_child, root, output) {
    alg_require(left_child instanceof Int32Array);
    alg_require(right_child instanceof Int32Array);
    alg_require(Number.isInteger(root) && root >= -2147483648 && root <= 2147483647);
    alg_require(output instanceof Int32Array);
    let n = left_child.length;
    alg_require(((n >= 0) && (n <= 1000000)));
    alg_require((left_child.length == n));
    alg_require((right_child.length == n));
    alg_require((output.length == n));
    alg_require(((root >= alg_sub(0, 1)) && (root < n)));
    for (let alg_i = 0; alg_i < left_child.length; alg_i++) {

Nov 15, 2026 javascript

Algorithms: Tree Algorithms

Iterative Binary Tree Preorder in Python

Preorder traversal visits each binary-tree node once without recursion..

python

def tree_preorder(left_child: list[int], right_child: list[int], root: int, output: list[int]) -> int:
    alg_require(isinstance(left_child, (list, tuple)) and len(left_child) <= 1000000)
    alg_require(isinstance(right_child, (list, tuple)) and len(right_child) <= 1000000)
    alg_require(type(root) is int and -2147483648 <= root <= 2147483647)
    alg_require(isinstance(output, list) and len(output) <= 1000000)
    n: int = len(left_child)
    alg_require(n >= 0 and n <= 1000000)
    alg_require(len(left_child) == n)
    alg_require(len(right_child) == n)
    alg_require(len(output) == n)
    alg_require(root >= -1 and root < n)
    for value in left_child:

Nov 15, 2026 python

Algorithms: Tree Algorithms

Iterative Binary Tree Preorder in C

Preorder traversal visits each binary-tree node once without recursion..

c

int tree_preorder(const int *left_child, size_t left_child_length, const int *right_child, size_t right_child_length, int root, int *output, size_t output_length) {
    int alg_error = 0;
    int alg_result = INT_MIN;
    errno = 0;
    int *stack = NULL;
    int *state = NULL;
    if (left_child_length > 1000000 || (left_child_length && !left_child)) { errno = EINVAL; alg_result = INT_MIN; goto alg_cleanup; }
    if (right_child_length > 1000000 || (right_child_length && !right_child)) { errno = EINVAL; alg_result = INT_MIN; goto alg_cleanup; }
    if (output_length > 1000000 || (output_length && !output)) { errno = EINVAL; alg_result = INT_MIN; goto alg_cleanup; }
    int n = (int)left_child_length;
    if (alg_error) { errno = ERANGE; alg_result = INT_MIN; goto alg_cleanup; }
    if (!(((n >= 0) && (n <= 1000000)))) { errno = EINVAL; alg_result = INT_MIN; goto alg_cleanup; }

Nov 15, 2026 C