212. Sort Colors

Medium
Dutch National Flag
Array

Problem

Given an array nums containing only 0, 1 and 2, sort the values in-place so equal values are adjacent and ordered 0, 1, 2. Return the sorted array.

Examples

Example 1

Input: [2,0,2,1,1,0]
Output: [0,0,1,1,2,2]

Example 2

Input: [2,0,1]
Output: [0,1,2]

Example 3

Input: [0]
Output: [0]
Constraints

1 <= nums.length <= 300

nums[i] is 0, 1 or 2.

Hints

?? Maintain regions for confirmed zeroes and confirmed twos.

?? The current pointer scans the unknown region.

Expected Complexity
Time: O(n)
Space: O(1)
Follow-up

Can you solve it in one pass using constant extra space?

Practice Notes

Attempts: 0

Time spent: 0min

Hints used: 0

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Case 1
Case 2
Case 3
Input
[2,0,2,1,1,0]
Expected
[0,0,1,1,2,2]