dsalgo 0.3.10

A package for Datastructures and Algorithms.
Documentation 
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pub fn safe_int_pow(
    x: u64,
    exponent: u8,
) -> Result<u64, &'static str> {
    if exponent == 0 {
        return Ok(1);
    }

    let mut y = safe_int_pow(x, exponent >> 1)?;

    debug_assert!(y > 0);

    const M: u64 = std::u64::MAX;

    if y > M / y {
        return Err("overflow");
    }

    y *= y;

    if exponent & 1 == 1 {
        if y > M / x {
            return Err("overflow");
        }

        y *= x;
    }

    Ok(y)
}

#[cfg(test)]

mod tests {

    #[test]

    fn test() {
        use super::*;

        assert!(safe_int_pow(2, 0).is_ok());

        assert!(safe_int_pow(2, 1).is_ok());

        assert!(safe_int_pow(2, 63).is_ok());

        assert!(safe_int_pow(2, 64).is_err());
    }
}