Codehs All Answers Karel Top May 2026

Before diving into specific answers, you must master these 5 helper functions. They appear in every "top" solution.

// Standard movement
function moveToWall() 
    while (frontIsClear()) 
        move();
// The classic turnaround
function turnAround() 
turnLeft();
turnLeft();

// Right turn (CodeHS doesn't have turnRight by default)
function turnRight() 
turnLeft();
turnLeft();
turnLeft();

// Put a ball if none exists
function safePutBall() 
if (noBallsPresent()) 
putBall();

// Safe pick up
function safeTakeBall() 
if (ballsPresent()) 
takeBall();
 codehs all answers karel top

Here are the solutions to the most frequent "stumping" problems students encounter early on.

Problem: Karel is at 1st Street, facing East. There are balls randomly placed on 1st Street (1st Avenue to 8th Avenue). Karel must collect all the balls and stop at 8th Avenue.

The Trap: Students write 8 if statements. That’s ugly. The "Top" Logic: Use a while loop that runs 8 times. Inside, check if a ball is present, pick it up, then move. Before diving into specific answers, you must master

Solution Blueprint (Pseudocode):

function start() 
    for(var i = 0; i < 8; i++) 
        while(ballsPresent()) 
            takeBall();
move();

Why this works: The while loop inside ensures Karel picks up all balls at a single spot before moving to the next avenue.

Task: Karel cleans up balls. Usually involves moving and taking balls.

def start():
    while frontIsClear():
        move()
        while ballsPresent():
            takeBall()

Task: Karel checks a ballot; if a ballot has a "vote" (ball), Karel removes it. If not, Karel leaves it. // Right turn (CodeHS doesn't have turnRight by

def start():
    while frontIsClear():
        check_ballot()
        move()
def check_ballot():
    if ballsPresent():
        takeBall()

Task: Pick up all balls in a pile and put down double that amount.

def start():
    while ballsPresent():
        takeBall()
        putBall()
        putBall()

These are the first hurdles. If you are stuck here, do not move on to advanced problems.

Problem: Cover the entire world (any size) with balls in a checkerboard pattern. A ball on (1,1), no ball on (2,1), ball on (1,2), etc.

The Trap: Nested loops that break on odd/even world sizes. The "Top" Logic: Move row by row. At the end of each row, turn around and go back. Alternate the starting column each row.

Solution Blueprint (Super Karel):

function start() 
    putBall(); // Start with a ball
    while(frontIsClear()) 
        moveAndAlternate();
function moveAndAlternate() 
    while(frontIsClear()) 
        move();
        if(ballsPresent()) 
            // If you are on a ball, don't do anything? No.
            // Actually: Alternating means toggle.
// Simpler: Move one step, then putBall if previous had none.

Real answer (short version):

function start() 
    var row = 1;
    while (true) 
        for (var i = 0; i < 8; i++) 
            if (row % 2 == i % 2) putBall();
            if (i < 7) move();
if (facingEast()) turnLeft();
        else turnRight();
        row++;
        if (!frontIsClear()) break;
        move();