This function, `left_child`, calculates the index of the left child...

This function, left_child, calculates the index of the left child of a node in a binary heap (typically represented as an array).

Details:

1. Parameter: The function takes an integer parent, which is the index of the parent node in the heap (array representation).
2. Logic: It uses the formula 2 * parent + 1 to compute and return the index of the left child of that parent node.

Context:

• In a binary heap, where the nodes are stored in a 0-based indexed array:
  • The left child's index is calculated as 2 * parent_index + 1.
  • The right child's index is calculated as 2 * parent_index + 2.

Example:

If the parent node has an index of 2:

• Left child's index = 2 * 2 + 1 = 5.

This function is typically used in algorithms involving heap data structures, such as heap sort or priority queues.