Selection algorithm of random probability in game development

The implementation code is ultra simple, and the specific implementation method is as follows:

Sometimes when our game characters encounter enemies, we need my monster to choose the processing method randomly according to the probability, as follows:
1. 50% chance of friendly greetings
2, 25% chance to walk away
3, 20% chance to attack immediately
4, 5% chance of giving money as a gift
The following algorithm is to follow the probability array and return the selected probability index number.

int Choose(float[]  Probability array )
{
   float total=0;
  // First, the total value of probabilities is calculated, which is used to calculate the random range 
   for(int i=0;i< Probability array .length;i++)
   {
      total+= Probability array [i];
   }
  Random rd = new Random();
  float  Random value =rd.Next(0,total);
  for(int i=0;i< Probability array .length;i++)
  {
      if( Random value < Probability array [i])
      {
          return i;
      }
      else
      {
           Random value -= Probability array [i];
      }
  }
   return  Probability array .length-1;
}

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