How to create a Method that would return indices of an element in some 2D array in java.

I am trying to generate a function find_indices(int num) in java which when called with a certain parameter would check the presence of that parameter in a 2D array say K,and would return its indices (indices in the matrix K).

I am talking about something similar like this:

int min=(int)Math.min(K[i][j],K[j][i]);
find_indices(min);
//
find_indices(int num)
{
//Now this method will return the indices of num in the 2D array K(if present)
}

Okay there are two things i have no idea about:

  • When i call a function that is supposed to return me two variables(i & j),how do i catch/hold/store them when they are returned?
  • I need an efficient way to search for num in the matrix K[][]. Since the number of testcases would be high,and on top of that if i use two for loops(O(n^2)searching technique) for each of such test cases, i guess i would run into a TLE. Hence i need to know the good ways to optimize searching process in a 2D array.

Any kind of help/suggestions regarding the above problems would be extremely helpful.
Thank you.

@codegagu : Regarding the return value , you can make a struct or class that has two integer fields and your return object can have those two fields set .

Regarding the efficiency of findIndices , how many times you need to find the min in same matrix , and does the matrix change in between and if yes how many entries are changed in one go ? You will have to spend initial n^2 time to find min entry but when updates happen you can always store the current min without doing n^2 operations .

Also if the initial matrix has some sort order or some property , you may not require the initial n^2 time also . You need to be more clear regarding your question .

Sorry for the lack of precision in the question. I missed one prominent part which is i have to find the minimum out of only two values in the matrix and not out of all the values,so that’s not much of my concern. I just don’t know how to work on the return value problem. Can you please elaborate more on the class with two integer fields and the return object with two field sets? Sorry i am a newbie so a little explanation or a code sample as an example will be extremely helpful.
thank you.

@codegagu : Just noticed you have asked it for Java .

In C or C++ , you could have used “struct”

In Java you need to make an “inner class” .

So suppose you have class called “Main” in which you are solving your problem and it looks like this

public class Main {

public class Point {

int x ;

int y ;

public Point (int xx ,int yy) {

x = xx;

y = yy;

}

static Main main;

public static void main (String[] args) {

main = new Main();

// here you call findIndices

Point p = findIndices();

int x = p.x;

int y = p.y;

}

public static Point findIndices() {

int ansX ;

int ansY ;

// you find ansX and ansY through some logic .

// then you make an object and return .

return main.new Point(ansX,ansY);

}

For more info you read about “inner classes in Java” on the internet .

Best of luck , cheers , happy coding .

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