Dutch National Flag Sort | Dataford Interview Questions

Implement the Dutch national flag algorithm to sort an array containing three distinct keys.

The function receives an array and three distinct keys defining the required order: key1, then key2, then key3. Sort the array in place and return it. Use a single traversal with constant extra space; do not call a built-in sorting function.

Constraints

1 <= len(nums) <= 1000
nums contains only key1, key2, and key3
key1, key2, and key3 are distinct
The required order is key1, key2, key3

Function Signature

def dutch_national_flag(nums, key1, key2, key3):

Your question is Dutch National Flag Sort. Start with the requirements in the Question tab.

Run and submit as often as you like. When you're ready, talk me through your approach or go straight to the code.

Problem

Implement the Dutch national flag algorithm to sort an array containing three distinct keys.

Constraints

1 <= len(nums) <= 1000
nums contains only key1, key2, and key3
key1, key2, and key3 are distinct
The required order is key1, key2, key3

Function Signature

def dutch_national_flag(nums, key1, key2, key3):

Your question is Dutch National Flag Sort. Start with the requirements in the Question tab.

Run and submit as often as you like. When you're ready, talk me through your approach or go straight to the code.