func divide(dividend int, divisor int) int {
    if dividend == 0 {
        return 0
    }
    if divisor == 1 {
        return dividend
    }
    if divisor == -1 {
        if dividend == -2147483648 {
            return 2147483647
        }
        return -dividend
    }
    var isSameSymbol bool
    if dividend < 0 && divisor < 0 {
        isSameSymbol = true
    } else if dividend > 0 && divisor > 0 {
        isSameSymbol = true
    }
    var dvd, dvs uint
    if dividend < 0 {
        if dividend == -2147483648 {
            dvd = 2147483648
        } else {
            dvd = uint(-dividend)
        }
    } else {
        dvd = uint(dividend)
    }
    if divisor < 0 {
        if divisor == -2147483648 {
            dvs = 2147483648
        } else {
            dvs = uint(-divisor)
        }
    } else {
        dvs = uint(divisor)
    }
    d := dvs
    bitNum := []uint{d}
    // 将 d 不断 *2，直到大于 dvd，此时 bitNum 中的最后一个值一定大于 dvd
    for d <= dvd {
        d = d << 1
        bitNum = append(bitNum, d)
    }
    var res int
    // 舍弃掉最后一个值
    i := len(bitNum) - 2
    for dvd >= dvs {
        if dvd >= bitNum[i] {
            dvd -= bitNum[i]
            // 2 ^ i 个 dvs
            res += 1 << i
        } else {
            i--
        }
    }
    if isSameSymbol {
        return res
    }
    return -res
}