Loop diagonally through two dimensional array

Question

I wrote the following code to walk half the diagonals of an array:

String[][] b = [a,b,c]
               [d,e,f]
               [g,h,i];  

public void LoopD         


        

Answer 1

This works for non-square arrays. It's simple to understand, but calls min() and max() once per diagonal.

int ndiags = width +  height - 1;
System.out.println("---");
for (int diag = 0; diag < ndiags; diag++) {
    int row_stop = Math.max(0,  diag -  width + 1);
    int row_start = Math.min(diag, height - 1);
    for (int row = row_start; row >= row_stop; row--) {
        // on a given diagonal row + col = constant "diag"
        // diag labels the diagonal number
        int col = diag - row;
        System.out.println(col + "," + row);
        relax(col, row);
    }
    System.out.println("---");
}

Here's output for width=3, height=3

---
0,0
---
0,1
1,0
---
0,2
1,1
2,0
---
1,2
2,1
---
2,2
---

width=3, height=2

---
0,0
---
0,1
1,0
---
1,1
2,0
---
2,1
---

width = 2, height = 3

---
0,0
---
0,1
1,0
---
0,2
1,1
---
1,2
---