Question

How to convert a 1D coordinate into 2D indexes in Java

Answer 1

public class MyClass {
    public static void main(String args[]) {
        int[][] array2d =
            {
                { 1,  2,   3,  6,  0},
                {-5, -4,   0,  7,  9},
                { 1, 18, 100, 14,  6},
                { 9, 10,  27, 12, 13}
            };
 
        int[] array1d = {1, 2, 3, 6, 0, -5, -4, 0, 7, 9, 1, 18, 100, 14, 6, 9, 10, 27, 12, 13};
 
        int cols = array2d[0].length;
     
        int index = 17;
 
        // int i = 3, j = 2;
 
        int i = index / cols;
        int j = index - (i * cols); // index % cols;
 
        System.out.println("i = " + i + " j = " + j);
 
        System.out.println(array1d[index]);
        System.out.println(array2d[i][j]);
    }
}

 
 
 
/*
run:
    
i = 3 j = 2
27
27
   
*/

 

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