题目：

题解：

func integerReplacement(n int) (ans int) {
    for n != 1 {
        switch {
        case n%2 == 0:
            ans++
            n /= 2
        case n%4 == 1:
            ans += 2
            n /= 2
        case n == 3:
            ans += 2
            n = 1
        default:
            ans += 2
            n = n/2 + 1
        }
    }
    return
}