Almost random filling of a two-dimensional C # array

Question

There is an array of 5x5. You need to fill it with zeros, and two randomly selected items

You can take two random numbers from 0 to 4, say 1 and 3, and then insert a unit in the array element with indices 1 and 3.

VladD VladD 183k sixteen 222 432 · Answer 1 · 2016-07-29T17:00:19

You basically need to select two random indexes from 0 to 24.

The easiest way to do this is using the standard Random :

With help
```
 i1 = random.Next(25) 
```
get the first index.
For the second index, 24 values remain, but it is necessary to choose among all the values not equal to i1 . The easiest way to do this is to write this:
```
 i2 = random.Next(24); if (i2 >= i1) i2++; 
```

Ok, now you need to turn each of the indexes into a double index from 0 to 4. This is done with

 x = i / 5; y = i % 5;

Further obvious. Fill the array with zeros, put units on two counted positions.

and how to make a random couple of elements? Use i3 = random.Next (23) and i4 = random.Next (22) ;;
only puts a new random element next to the previous random element
@RustemValeev: If you need a sample of k random elements, it is easier, probably, to make a selection of random elements, as described here (second block of code), only to lead not to n , but to k (in your case 4).

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