Codehs 8.1.5 Manipulating 2d Arrays 〈95% TRUSTED〉

A: Use arr[i].length for each row in the inner loop. Avoid arr[0].length if rows have different sizes. Conclusion CodeHS 8.1.5, "Manipulating 2D Arrays," is a rite of passage for aspiring Java developers. It forces you to master nested loops, index math, and algorithmic thinking. By understanding how to swap rows, swap columns, and rotate matrices, you are building the spatial reasoning required for technical interviews, game programming, and data science.

// Swap two rows by reference public static void swapRows(int[][] arr, int r1, int r2) { int[] temp = arr[r1]; arr[r1] = arr[r2]; arr[r2] = temp; } Codehs 8.1.5 Manipulating 2d Arrays

public static void swapRows(int[][] arr, int rowA, int rowB) { int[] temp = arr[rowA]; arr[rowA] = arr[rowB]; arr[rowB] = temp; } Note: If your 2D array uses ArrayList<ArrayList<Integer>> , you’ll need a deep swap, but for standard [][] , this works perfectly. Prompt: Write a method swapColumns(int[][] arr, int colA, int colB) . A: Use arr[i]

// Manipulation task 8.1.5 specific: Create diagonal pattern public static void diagonalOne(int[][] arr) { for (int r = 0; r < arr.length; r++) { for (int c = 0; c < arr[0].length; c++) { if (r == c) { arr[r][c] = 1; } else if (r + c == arr.length - 1) { arr[r][c] = 1; // Anti-diagonal also to 1 } else { arr[r][c] = 0; } } } } It forces you to master nested loops, index