Talk is cheap.

递归法 递归深度大，不推荐。

func lastRemaining(n int, m int) int {
    if n <= 0 || m <= 0 {
        return -1
    }
    if n == 1 {
        return 0
    }
    return (lastRemaining(n - 1, m) + m) % n
}

循环迭代法

func lastRemaining(n int, m int) int {
    if n <= 0 || m <= 0 {
        return -1
    }
    last := 0
    for i := 2; i < n + 1; i++ {
        last = (last + m) % i
    }
    return last
}