CODEWITHSUNDEEP
c++optimizationmatrixwhile-loopsentinel
Zoltán Schmidt
Zoltán Schmidt

Reputation: 1345

An optimal way of finding the first row with only '0' elements in matrix?

I won't diguise it: I got an optimization homework for a programming task, and I need a confirmation about that my solution right.

The task is the next: you get a matrix that has random number of rows, and each row has different length. There are sentinels in the matrix we get: there's a -1 value at the end of each row. The last row of the matrix starts with a -1 value. Every other values of the matrix are positive integers and 0.

The task is to find the first row, that has only 0 elements (excluding the sentinel, and write it - also, I have to use only 2 variable, one while loop, and one condition within it. Writing out may happen with conditions.

Overall, the code must have a general form like this (excluding the definition of the matrix:

//'sor' means row, 'oszlop' means coloumn

int sor, oszlop;

while(){
    if(){

    }else{

    };
}

if (){
cout <<"We couldn't find a row with only 0 elements."<<end; 
}else{                                      
cout <<"We could, and this is:"<<end;   
}

And this is my code (only the parts inside main(), and also excludes the definition of the matrix):

int sor=0, oszlop=0;                    

while (x[sor][oszlop]!=-1){             
    if (x[sor][oszlop]==0){ 
        ++oszlop;           
    }else{      
        ++sor;  
        oszlop=0;           
    }
}

if (oszlop==0){
cout <<"We couldn't find a row with only 0 elements."<<end; 
}else{                                      
cout <<"We could, and this is:"<<end;   
}

The code skips invalid coloumns, until it reaches the end; or it exits if it can reach the end of any rows - but it can do it only if all of its elements were 0.

It definitely exits in case of finding a -1, but the value of oszlop decides, whether we found a valid row, or we couldn't, and we exit because of reaching end of the matrix.

I tested it with a random matrix, but I'm still unsure, so I need your confirmation.

Did I do the task well?

Upvotes: 0

Views: 144

Answers (1)

Tyler Brabham
Tyler Brabham

Reputation: 218

Did you try testing it on a matrix where the only valid row is the last row? Say for example,

[-1;
-1 0 -1]

Or perhaps

[1 -1;
-1 0 -1]

if every row has to have some element other than -1.

Upvotes: 0

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