The expression (row + col) % 2 divides the sum of the indexes by 2 and checks the remainder. A remainder of 0 means the sum is even, triggering the primary color. Common Mistakes and How to Debug Them
) to create a grid where colors alternate both horizontally and vertically. 1. Initialize the Grid
FOR row FROM 0 TO total_rows - 1: FOR col FROM 0 TO total_cols - 1: IF (row + col) % 2 == 0: PRINT "X" ELSE: PRINT "O" PRINT NEWLINE Use code with caution. Common Pitfalls and Troubleshooting
def print_board(board): for i in range(len(board)): print(" ".join([str(x) for x in board[i]]))
Depending on the specific platform you are using, the assignment is typically implemented in either or JavaScript . 1. Java Implementation (CodeHS Style) 9.1.7 checkerboard v2 answers
s using a nested loop. The most efficient way to achieve this pattern is by checking if the sum of the current row index ( ) and column index ( ) is even or odd. Python Solution
Understanding how to build this visual grid efficiently is a major milestone for beginner programmers. This comprehensive guide breaks down the core concepts, logic patterns, and implementation strategies required to solve it. Understanding the Core Problem
def build_checkerboard(rows, cols): board = [] for i in range(rows): row = [] for j in range(cols): if (i + j) % 2 == 0: row.append(0) else: row.append(1) board.append(row) return board
public class CheckerboardV2 public static void main(String[] args) int rows = 8; int cols = 8; for (int r = 0; r < rows; r++) for (int c = 0; c < cols; c++) if ((r + c) % 2 == 0) System.getProperties(); System.print("1 "); // Represents Color A else System.print("0 "); // Represents Color B System.println(); // Move to next row Use code with caution. Common Mistakes and How to Debug Them The expression (row + col) % 2 divides
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Do not use fixed numbers like 8 inside your loop conditions if your exercise provides variables like NUM_ROWS or getWidth() . Hardcoded grids will fail automated test cases that pass different grid sizes to your code. 2. Nesting Loops Invertedly
: The for j in range(size) loop builds the string for that specific row by adding characters one by one 0.5.3 .
: Move to a new line once the inner loop finishes a row. Pseudo-Code Example 4. Print the Result
Start by creating a 2D list (grid) that contains 8 rows and 8 columns, with all elements initially set to 0. 2. Iterate Through Rows and Columns
# Function to print the board as required by the exercise def print_board(board): for row in board: print(" ".join([str(x) for x in row])) # 1. Initialize an 8x8 grid with all 0s my_grid = [] for i in range(8): my_grid.append([0] * 8) # 2. Use nested loops to apply the checkerboard pattern for row in range(8): for col in range(8): # Use modulus on the sum of row and col to find "odd" positions if (row + col) % 2 == 1: my_grid[row][col] = 1 # 3. Print the final board print_board(my_grid) Use code with caution. Copied to clipboard Key Logic Points
Additionally, the print_board function utilizes a single loop to iterate through the rows. The use of " ".join([str(x) for x in board[i]]) elegantly handles formatting, making the output clean and readable.
To create the checkerboard pattern, an element should be a 1 if the sum of its row and column indices is even (or odd, depending on the desired starting color). Use the modulus operator to check this condition: if (row + col) % 2 == 0: grid[row][col] = 1 Use code with caution. Copied to clipboard : Sets the element to 1 . Odd sum (row + col) : Leaves the element as 0 . 4. Print the Result
