CODEWITHSUNDEEP
javaarraysmatrix
John
John

Reputation: 107

How to use conditional statement to check whether array equal to a row of matrix?

I have an array of int type, I want check that if all elements of this array are equal to the elements of i-th row of m×n matrix. For example: 

array={5,0,2,3};

and 

matrix={{1,3,2,2}{5,0,2,3}{2,1,2,9}};

so if 

array[j] = matrix[i][j];

for all j=0,1,2 then 

print("the wanted i is: "+i);

I have written this code:

public static void main(String[] args){
    int i, j, m=3, n=4;
    int[][] A0 = {{0,2,2,5},{2,0,3,1},{0,2,0,5}}; 
    int[] A={0,2,0,5};
    int seq = 0;
    for(i=0;i<m;i++){
       for(j=0;j<n;j++){
          if(A[j] != A0[i][j]){
             break;
          }
          seq= i;
       }
    }
    System.out.print(seq);
}

But its not work well because it always continue checking until final row.
Is there is any other better idea? Many thanks.

Upvotes: 1

Views: 417

Answers (5)

Manish
Manish

Reputation: 59

public static void main(String[] args){
    int i, j, m=3, n=4;int ct=0;
    int[][] A0 = {{0,2,2,5},{2,0,3,1},{0,2,0,5}}; 
    int[] A={0,2,0,5};
    int seq = 0;
    for(i=0;i<m;i++){
       for(j=0;j<n;j++){
          if(A[j] == A0[i][j]){
           ct++;
          } 
          else
          {
              break;
              }

           }
       if(ct==4)
       { 
           seq=i;
           break;
       }

       ct=0;
    }
    System.out.print(seq);
}

Upvotes: 1

Jason Camiller
Jason Camiller

Reputation: 11

    private int[][] myArray;

    public boolean equalsRow(int[] row, int x) 
    {
       return Arrays.equals(row, myArray[x]);
    }

simpler

Upvotes: 1

janos
janos

Reputation: 124804

First of all, if any value is different in a row, then you want to skip to the next iteration of the outer loop. You can do that by giving the outer loop a label, and the continue statement.

Secondly, as soon as you found a row where all values match, you can break out of the outer loop.

    OUT: for (i = 0; i < m; i++) {
        for (j = 0; j < n; j++) {
            if (A[j] != A0[i][j]) {
                continue OUT;
            }
        }
        seq = i;
        break;
    }

By using Arrays.equals you can simplify by quite a lot, by eliminating the inner loop, and with it all the label + continue black magic:

    for (i = 0; i < m; i++) {
        if (Arrays.equals(A, A0[i])) {
            seq = i;
            break;
        }
    }

Upvotes: 2

Raffaele
Raffaele

Reputation: 20885

You can simply use Arrays.equals()

private int[][] matrix;

public boolean equalsRow(int[] row, int index) {
  return Arrays.equals(row, matrix[index]);
}

Upvotes: 1

Bruno Caceiro
Bruno Caceiro

Reputation: 7199

You have two forconditions. So when you reach

if(A[j] != A0[i][j]) {
   break;
}

You will break the only this for loop, so you will continue the other loop:

 for(i=0;i<m;i++) {

So you have to break this one too, here is a solution

boolean canBreak = false;
for(i=0;i<m;i++) {
    for(j=0;j<n;j++) {
        if(A[j] != A0[i][j]) {
            canBreak = true;
            break;
        }
        if (canBreak) break;
        seq= i;
    }
}

Upvotes: 1

Related Questions