#0063

Generate Permutations

MediumDSA30 min20 XP

Problem

Given a list of distinct values, return a list containing all permutations. The output order does not matter.

Why This Matters

Backtracking is controlled trial and undo. This problem is the cleanest way to understand choose, explore, unchoose.

Function Signature

def permutations(items):

Examples

Example 1

Input[1, 2, 3]

Outputsix permutations

There are 3 choices for the first position, then 2, then 1.

Constraints

Items are distinct.
Return [[]] for an empty input.
Output order does not matter.

CodePython

def permutations(items):
    """
    Input example: [1, 2, 3]
    Return: six permutations
    Return the value from the function so the tests can compare it. Do not print unless the prompt asks.
    """
    # write your code here
    return []

def permutations(items):
    """
    Input example: [1, 2, 3]
    Return: six permutations
    Return the value from the function so the tests can compare it. Do not print unless the prompt asks.
    """
    # write your code here
    return []

Visible browser tests run here when available.

Testcases1 visible / 3 hidden categories

Three items

Input[1, 2, 3]

Expected6 permutations

3 factorial equals 6.

Hidden Test Categories

Empty inputOne itemString values