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Sort Colors

Given an array with n objects colored red (0), white (1), or blue (2), sort them in-place so same colors are adjacent in order 0, 1, 2.

Output space-separated.

Input:

2,0,2,1,1,0

Output:

0 0 1 1 2 2

Reasoning:

The input array is 2, 0, 2, 1, 1, 0, which needs to be sorted in-place with same colors adjacent in order 0, 1, 2.
We initialize three pointers: one at the start, one at the end, and one for scanning the array, to track the positions of 0, 1, and 2.
As we scan the array, we swap elements to maintain the order: if the current element is 0, we swap it with the element at the start pointer and move both pointers forward; if it's 2, we swap it with the element at the end pointer and move the end pointer backward.
After scanning the entire array, the elements are sorted in-place as 0, 0, 1, 1, 2, 2, which is then output as space-separated values: 0 0 1 1 2 2.

Editor

Python 3.13.1

0/0

Run code to see test results.