Given a list containing only the values 0, 1, and 2, sort the list in ascending order so all 0s come first, then all 1s, then all 2s. Do not use the built-in sort() method. Use the Dutch National Flag algorithm with three pointer variables to solve this in a single pass.

Examples:

Input: nums = [2, 0, 2, 1, 1, 0] Output: [0, 0, 1, 1, 2, 2] Explanation: All 0s first, then 1s, then 2s Input: nums = [2, 0, 1] Output: [0, 1, 2] Explanation: One of each value sorted in order Input: nums = [0] Output: [0] Explanation: Single element, no sorting needed Input: nums = [1, 1, 0, 2, 0, 1] Output: [0, 0, 1, 1, 1, 2] Explanation: Two 0s, three 1s, one 2 Input: nums = [2, 2, 2] Output: [2, 2, 2] Explanation: All same values, no change needed
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