lavos/cap3/ex38.go

package cap3

func Ex38(k int, nums []int) {
	gcd := func(m, n int) int {
		a, b := m, n
		if m < n {
			a, b = n, m
		}

		r := a % b
		for r != 0 {
			a = b
			b = r
			r = a % b
		}

		return b
	}

	numsLen := len(nums)
	first, gcdNumb := 0, gcd(numsLen, k)
	for i := 0; i < gcdNumb; i++ {
		first = nums[i]
		startIdx := i
		for j := 0; j < numsLen/gcdNumb; j++ {
			startIdx = (startIdx + k) % numsLen
			// 交换
			tmp := nums[startIdx]
			nums[startIdx] = first
			first = tmp
		}
	}
}