Consider the following method declaration. public static void increment(int[][] a) { for (int r = 0; r

Question

Consider the following method declaration.

public static void increment(int[][] a)
{
  for (int r = 0; r < a.length; r++)
  {
    for (int c = 0; c < a[0].length; c++)
    {
      if (a[r][c] >= 0)
        a[r][c] += 2;
      else
        a[r][c] -= 2;
    }
  }
}

Assume the 2D array, matrix, has been initialized to the following values:

2     9    -10
3     0    -4
-10  -4    -1

What is the value of matrix after the method call, increment(matrix);?

BlackTom AI · Accepted Answer

Each non-negative entry is increased by 2 and each negative entry is decreased by 2, as dictated by the if (a[r][c] >= 0) a[r][c] += 2; else a[r][c] -= 2; The nested loops visit every row r (0..a.length-1) and every column c (0..a[0].length-1); using a[0].length is fine here because the matrix is a rectangular 3×3 array. Start with the initial matrix, and apply the rule to each element, showing intermediate steps: Row 0: - a[0][0] = 2 (>= 0) → 2 + 2 = 4 - a[0][1] = 9 (>= 0) → 9 + 2 = 11 - a[0][2] = -10 (< 0) → -10 - 2 = -12 Row 1: - a[1][0] = 3 (>= 0) → 3 + 2 = 5 - a[1][1] = 0 (>= 0) → 0 + 2 = 2 - a[1][2] = -4 (< 0) → -4 - 2 = -6 Row 2: - a[2][0] = -10 (< 0) → -10 - 2 = -12 - a[2][1] = -4 (< 0) → -4 - 2 = -6 - a[2][2] = -1 (< 0) → -1 - 2 = -3 Putting the transformed entries into matrix form yields: 4 11 -12 5 2 -6 -12 -6 -3 Why this is correct: each element was tested against >= 0 and adjusted exactly as the method prescribes. Common mistakes would be to (a) add 2 to negative numbers (which would produce -8, -2, etc.), (b) subtract 2 from non-negatives (which would produce 0, 7, etc.), or (c) mis-index rows/columns. None of those match the computed values above. Final answer confirmed: 4 11 -12 5 2 -6 -12 -6 -3

类似问题

Which statement declares a two-dimensional integer array called myArray with 3 rows and 4 columns?

What is the output of the following code: int arr[4][4] = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16}; for (int j = 2; j < 3; j++) for(int i = 0; i < 4; i++) cout << arr[i][j];

Consider the following code segment. int[][] mat = new int[4][6]; for (int r = 0; r < 4; r++) { for (int c = 0; c < 6; c++) { if(c < 3 - r || c > 3 + r) { mat[r][c] = 0; } else { mat[r][c] = 1; } } } Which of the following represents mat after this code segment is executed?

Consider the following method intended to swap the first and second rows in a two-dimensional array: public static void swapRow(int[][] a) { /* missing code / } Which of the following correctly replaces / missing code */?

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