C#•14mo ago

How to optimize this?

I have following:

using System;

namespace SquareCalculus
{
    internal class FigureTriangle : IFigure
    {
        private readonly double _sideA;
        private readonly double _sideB;
        private readonly double _sideC;

        public FigureTriangle(
            double sideA,
            double sideB,
            double sideC)
        {
            ArgumentOutOfRangeException.ThrowIfNegativeOrZero(sideA, nameof(sideA));
            ArgumentOutOfRangeException.ThrowIfNegativeOrZero(sideB, nameof(sideB));
            ArgumentOutOfRangeException.ThrowIfNegativeOrZero(sideC, nameof(sideC));

            _sideA = sideA;
            _sideB = sideB;
            _sideC = sideC;
        }

        public double CalculateSquare()
        {
            var perimetr = (_sideA + _sideB + _sideC) / 2;

            var square = Math.Sqrt(perimetr
                * (perimetr - _sideA)
                * (perimetr - _sideB)
                * (perimetr - _sideC));

            return square;
        }

        public bool IsRightTriangle()
        {
            var sides = new double[] { _sideA, _sideB, _sideC };

            Array.Sort(sides);

            return Math.Pow(sides[2], 2) == Math.Pow(sides[0], 2) + Math.Pow(sides[1], 2);
        }
    }
}

using System;

namespace SquareCalculus
{
    internal class FigureTriangle : IFigure
    {
        private readonly double _sideA;
        private readonly double _sideB;
        private readonly double _sideC;

        public FigureTriangle(
            double sideA,
            double sideB,
            double sideC)
        {
            ArgumentOutOfRangeException.ThrowIfNegativeOrZero(sideA, nameof(sideA));
            ArgumentOutOfRangeException.ThrowIfNegativeOrZero(sideB, nameof(sideB));
            ArgumentOutOfRangeException.ThrowIfNegativeOrZero(sideC, nameof(sideC));

            _sideA = sideA;
            _sideB = sideB;
            _sideC = sideC;
        }

        public double CalculateSquare()
        {
            var perimetr = (_sideA + _sideB + _sideC) / 2;

            var square = Math.Sqrt(perimetr
                * (perimetr - _sideA)
                * (perimetr - _sideB)
                * (perimetr - _sideC));

            return square;
        }

        public bool IsRightTriangle()
        {
            var sides = new double[] { _sideA, _sideB, _sideC };

            Array.Sort(sides);

            return Math.Pow(sides[2], 2) == Math.Pow(sides[0], 2) + Math.Pow(sides[1], 2);
        }
    }
}

Imagine I will call IsRightTriangle twice with the same parameters. It is not optimal to do sorting etc again again.. So how can I fix it?

7 Replies

dan in a can•14mo ago

since all the side variables are class level anyway, why not make sides class level?

x0rld•14mo ago

the sides + sort can be made in the ctor also

cap5lut•14mo ago

and no matter where, dont allocate an array for 3 elements to sort it. use a Span<T> for CalculateSquare u can probably also use SIMD, tho i guess u will need to benchmark if it really will have some influence and it probably maybe be a readonly struct

SWEETPONYOP•14mo ago

thanks for advices maybe Im wrong but can Lazy help me?

cap5lut•14mo ago

not really worth it, either precompute it or compute it every time did u actually benchmark it and the results have shown that this is a bottle neck, or is this premature optimization btw?

SWEETPONYOP•14mo ago

hm no but it is a test task from company and I’d like to write as good as I can

cap5lut•14mo ago

in the end its a matter of if u need to preserve the order of the sides, or if u can sort them at construction but all of this also sorta shouts that this can be a readonly struct

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