75. Sort Colors

Given an array nums with n objects colored red, white, or blue, sort them **in-place **so that objects of the same color are adjacent, with the colors in the order red, white, and blue.

Here, we will use the integers 0, 1, and 2 to represent the color red, white, and blue respectively.

Follow up:

• Could you solve this problem without using the library's sort function?
• Could you come up with a one-pass algorithm using only O(1) constant space?

Example 1:

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

Example 2:

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

Example 3:

Input: nums = [0]
Output: [0]

Example 4:

Input: nums = [1]
Output: [1]

Constraints:

• n == nums.length
• 1 <= n <= 300
• nums[i] is 0, 1, or 2.

# @lc code=start
using LeetCode

function sort_colors!(nums::Vector{Int})
    left = 1
    for i in eachindex(nums)
        if nums[i] == 0
            nums[i], nums[left] = nums[left], nums[i]
            left += 1
        end
    end
    for i in (left + 1):length(nums)
        if nums[i] == 1
            nums[i], nums[left] = nums[left], nums[i]
            left += 1
        end
    end
end

# @lc code=end

sort_colors! (generic function with 1 method)

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