Re: 2d array element change

From:
"Alf P. Steinbach" <alf.p.steinbach+usenet@gmail.com>
Newsgroups:
comp.lang.c++
Date:
Sun, 01 Dec 2013 03:01:15 +0100
Message-ID:
<l7e59h$aiv$1@dont-email.me>
On 01.12.2013 02:27, axcytz@gmail.com wrote:

I have 2d array (10x12), and they have 0 and 1s in them. I want to count
the 1s in each array and I have two cases here: (1) if an array has more
than three 1s, say k many, then generate k - 3 random variables and replace
that many 1s with 0s if that random variable corresponds to a 1. (2)if an
array has less than three 1s, say q many, then generate 3 - q random
variables and replace that many 0s with 1s if that random variable
corresponds to a 0. I have the following code so far. I need some suggestions
here, I could not construct the code well.


Is this a fair restatement:

* You have 10 arrays, each of 12 items, each item is either 0 or 1.
* In each array:
   - Let n = count of 1 values in the array.
   - If n < 3, then randomly change 0s into 1s until n = 3.
   - If n > 3, then randomly change 1s into 0s until n = 3.

?

int y[10];
int r[10];

for(int i=0; i < 10; i++){
         for(int j=0; j < 12; j++)
         {
             y[i] += Array[i][j];
         }


You are not guaranteed that `y` is all zeroes, since `y` is a non-static
variable.

To guarantee all zeros you need to explicitly /zero-initialize/:

     int y[10] = {};

But if you use a `std::vector` then its constructor will do it for you:

     vector<int> y(10);

         if(y[i] > 3)
         {
             f = y[i] - 3;
             if(Array[i][r[f]] ==1)
             Array[i][r[f]] = 0;


This part doesn't appear meaningful.

Presumably this part is what you're seeking help with?

Cheers,

- Alf

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