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Sort Colors
MediumVerifiedTwo PointersSortingArray~20 min
Given an array nums of 0s, 1s, and 2s, sort it so the colors group in order.
The Dutch-national-flag scan keeps three pointers — low, mid, high — and swaps in one pass.
The input arrives as a single array nums. Return the sorted array.
Examples
in[2, 0, 2, 1, 1, 0]
out[0, 0, 1, 1, 2, 2]
All 0s, then 1s, then 2s.
in[2, 0, 1]
out[0, 1, 2]
Three colors sorted in place.
Constraints
- 1 ≤ nums.length ≤ 300
- nums[i] is 0, 1, or 2.
- Target: one pass, constant extra space
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