How to count how many maximum are in an array ?

Question

3.00/5 (1 vote)

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i have this function, and i want you're help to find if there is more than one maximum i want to print:

C#

No unique max.

What I have tried:

C#

int find_max(int b[N][N])
{
   nt max = b[0][0];
   int x,y;
   int counter=0;
   int a=0,v=0,c=0;
   for (x = 0; x < N; x++)
   {
       for (y = 0; y < N; y++)
       {
           if (max < b[x][y])
           {
               max = b[x][y];
                a=x;
                v=y;
           }
       }
   }

    c=((a*10)+v);
    for (x = 0; x < N; x++)
   {
       for (y = 0; y < N; y++)
       {
           if((b[x][y]) == max);
           counter++;
       }
   }
 if(counter>1)
   printf("no uniqe max");
else
   return c;
}

Posted 12-Jun-16 12:02pm

molan77

Updated 12-Jun-16 16:36pm

v6

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Comments

George Jonsson 12-Jun-16 18:52pm

printf returns the number of characters written, so this line will be confusing for you.
return(printf("No unique max."));

George Jonsson 12-Jun-16 19:53pm

After your change in the code it will not compile, because all paths doesn't have a return value.

Patrice T 12-Jun-16 19:45pm

Give an example with more than 1 maximum

molan77 12-Jun-16 20:03pm

there is many examples , why ?

Patrice T 13-Jun-16 0:39am

Put an example in question.
Use Improve question to update your question.
So that everyone can pay attention to this information.

George Jonsson 12-Jun-16 19:55pm

From your previous question, my understanding was that you wanted to find the maximum in a one dimensional array, not a two dimensional.

molan77 12-Jun-16 20:02pm

no i wanted to find tha max in 2D array !i want to find if there is max in more than one place in the array ... so i did a loop to find the place of max and update the counter ...

George Jonsson 12-Jun-16 20:47pm

According to your previous question (How can I write a C program find the number of the winner?[^]) you need to find the max for both red and blue votes and then combine them into a number, like
Blue: 1 6 2 5 3 3 Max = 6
Red : 2 1 7 3 1 2 Max = 7
And the answer should be 67.
Or have I misunderstood completely?

molan77 12-Jun-16 21:00pm

i think you misunderstood , i used 2D array,i changed the answer you gave me a bit on the previus question, then lats say the input was 44 42 .. then the place i=4 and j=4 will become 1 instead of 0..
then i found the maz, which means the number of two digits that was most repeated, and this function finds if there is more than one max ...
but the counter thing is not woking :(

George Jonsson 12-Jun-16 21:56pm

Of course it is not working. Where do you set the variable k?

Now it is time for you to start to think a bit on your own.

molan77 12-Jun-16 22:01pm

why this mystrious hint , what is wrong with k my brain stoped to function(it is 5 am where i live lol )

molan77 12-Jun-16 22:09pm

ok lol i got it , k=0 so it is wrong to say if(k==max)
so i delete k, but it still tils me "suggest braces around empty body in c" why ...

George Jonsson 12-Jun-16 23:13pm

Look for an oddly placed semicolon (;)

molan77 12-Jun-16 20:34pm

i will cheat of the return thing lol , i will just do if counter>1 return 999 and then when want to use the output of the function i will use if statement, if output=999 printf ("no un...") else(...)
now my problem is that the function doesn't pay atintion if the max is repeated , it doesn't work !

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Sergey Alexandrovich Kryukov · Accepted Answer · 2016-06-12T12:34:00

First of all, there is exactly one maximum. More exactly, an arbitrary functions which may have infinite number of points, which values have relationship of order defined, may or may not have a maximum, but for the arrays, which are have finite number of elements, there is one maximum. What is multiple? The set of array indices on which the maximum value of element is achieved. How to count them?

One obvious solution is: in first loop (in your case, this is a nested loop) you find the maximum value itself. When it is done, traverse all the values again in the similar nested loop, and count the number of cases (combination of x, y pairs of indices) where the maximum is achieved.

I hope the bug in your existing algorithm is quite obvious. Let's see: when you assign new value to max, you always increment the counter. But, in general case, the value of max is not equal to the maximum value yet, so you increment the counter more times that you really should.

As I can see, you have quote enough knowledge to fix your code using my suggestion. Please do it.

—SA