public static readonly int RATIO_CHANCE_A = 10;

public static readonly int RATIO_CHANCE_B = 30;

//                         ...

public static readonly int RATIO_CHANCE_N = 60;

​

public static readonly int RATIO_TOTAL = RATIO_CHANCE_A

                                       + RATIO_CHANCE_B

                                         // ...

                                       + RATIO_CHANCE_N;

​

Random random = new Random();

int x = random.Next(0, RATIO_TOTAL);

​

if ((x -= RATIO_CHANCE_A) < 0) // Test for A

{ 

     do_something1();

} 

else if ((x -= RATIO_CHANCE_B) < 0) // Test for B

{ 

     do_something2();

}

// ... etc

else // No need for final if statement

{ 

     do_somethingN();

}

​

public static readonly int RATIO_CHANCE_A = 10;

public static readonly int RATIO_CHANCE_B = 30;

//                         ...

public static readonly int RATIO_CHANCE_N = 60;

​

public static readonly int RATIO_TOTAL = RATIO_CHANCE_A

                                       + RATIO_CHANCE_B

                                         // ...

                                       + RATIO_CHANCE_N;

​

Random random = new Random();

int x = random.Next(0, RATIO_TOTAL);

​

if ((x -= RATIO_CHANCE_A) < 0) // Test for A

{ 

     do_something1();

} 

else if ((x -= RATIO_CHANCE_B) < 0) // Test for B

{ 

     do_something2();

}

// ... etc

else // No need for final if statement

{ 

     do_somethingN();

}

​

​

private int RandWeight(List<float> weights)

    {

        float weightSum = 0f;

        for (int i = 0; i < weights.Count; ++i)

        {

            weightSum += weights[i];

        }

​

        float randomValue = Random.Range(0, weightSum);

        int index = 0;

        float tmpSum = 0f;

        while (!(tmpSum <= randomValue && (tmpSum + weights[index]) >= randomValue))

        {

            tmpSum += weights[index];

            index++;

        }

        return index;

    }