Sort an Array of 0s and 1s

Problem Given an array containing only 0s and 1s, sort it in place so that all 0s precede all 1s.

Input / Output

• Input: array nums containing only the values 0 and 1.
• Output: the same array, mutated in place, with every 0 before every 1.

Constraints

• Must be in place — O(1) extra space, no auxiliary array.
• Single pass preferred; a counting solution that rewrites the array is a valid but weaker answer.
• 0 <= nums.length <= 10^5.

Example

• [1,0,1,0,0,1] -> [0,0,0,1,1,1].
• Edge cases: all-zeros [0,0] and all-ones [1,1] are already sorted and must survive untouched; an empty array returns immediately.