10 矩形覆盖

func rectCover( number int ) int {
    // write code here
    if number == 0 {
        return 0
    }
    if number == 1 {
        return 1
    }
    if number == 2 {
        return 2
    }
    a, b, c := 1, 2, 0
    for ; number > 2; number-- {
        c = a + b 
        a = b 
        b = c
    }
    return c 
}