To pass the CodeHS autograder, you can't just print the numbers; you must actually values to a 2D list using nested for-loops.
The main function drives the entire program. It uses a while (leftIsClear()) loop to ensure that as long as there is a row above to move to, Karel keeps working. The final fillRow() ensures the last row is filled. fillRow() Function This is the core logic. Karel starts by placing a beeper.
The most common mistake is simply "cheating" the output with a print statement. The CodeHS autograder specifically checks for (e.g., board[i][j] = 1 ). If you don't use these, you'll see a red error message: "You should set some elements of your board to 1." .
Square Size=Canvas WidthNumber of ColumnsSquare Size equals the fraction with numerator Canvas Width and denominator Number of Columns end-fraction 9.1.6 checkerboard v1 codehs
By understanding the logic and code for the "9.1.6 Checkerboard, v1" exercise, you've taken a significant step toward mastering 2D lists and building the foundation for more complex projects in your Python journey.
Implementing a grid-based graphics program is a classic milestone in learning computer science. In the CodeHS JavaScript Graphics curriculum, the assignment challenges you to combine loops, nested structures, and geometric math to draw a classic checkerboard pattern on the screen.
: This is the most efficient way to toggle between two states (even/odd). To pass the CodeHS autograder, you can't just
CodeHS Introduction to Programming (JavaScript) Module: 9.1 - Karel Challenges Problem: 9.1.6 Checkerboard v1 Objective: Write a Karel program that places a checkerboard pattern of beepers on a rectangular world of any size (within Karel’s limits).
for i in range(8): row = [] for j in range(8): if (i + j) % 2 == 0: row.append("R") # R for red else: row.append("B") # B for black board.append(row)
This article breaks down the logic, the math, and the exact code structure needed to solve this exercise efficiently. Understanding the Goal The final fillRow() ensures the last row is filled
If you add the current row index ( r ) and column index ( c ), the sum alternates between even and odd numbers across the entire grid: Row 0, Col 0 Row 0, Col 1 Row 1, Col 0 Row 1, Col 1
: Create a 2D list (an 8x8 grid) filled entirely with 0s.
: Some variations or autograders may require initializing the board with 0s first and then using nested loops to selectively assign to specific indices (e.g., board[i][j] = 1 Autograder Requirements : To pass all tests on , ensure you are using assignment statements