LeetCode/go/sort-an-array.go

package main

func sortArray(nums []int) []int {
	swap := func(i, j int) {
		nums[i], nums[j] = nums[j], nums[i]
	}

	partition := func(lower, upper int) (int, int) {
		pivot := nums[(lower+upper)/2]

		lt, eq, gt := lower, lower, upper

		for eq <= gt {
			if nums[eq] < pivot {
				swap(eq, lt)
				lt++
				eq++
			} else if nums[eq] > pivot {
				swap(eq, gt)
				gt--
			} else {
				eq++
			}
		}

		return lt, gt
	}

	var quicksort func(int, int)
	quicksort = func(lower, upper int) {
		if lower >= upper || lower < 0 || upper < 0 {
			return
		}

		lt, gt := partition(lower, upper)
		quicksort(lower, lt-1)
		quicksort(gt+1, upper)
	}

	quicksort(0, len(nums)-1)
	return nums
}