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.
We will use the integers 0
, 1
, and 2
to represent the color red, white, and blue, respectively.
You must solve this problem without using the library's sort function.
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]
Constraints:
-
n == nums.length
-
1 <= n <= 300
-
nums[i]
is either0
,1
, or2
.
Follow up: Could you come up with a one-pass algorithm using only constant extra space?
SOLUTION:
class Solution:
def partition(self, nums, x, beg, end):
i = beg
for j in range(beg, end):
if nums[j] <= x:
nums[i], nums[j] = nums[j], nums[i]
i += 1
return i
def sortColors(self, nums: List[int]) -> None:
n = len(nums)
i = self.partition(nums, 1, 0, n)
self.partition(nums, 0, 0, i)
return nums
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