[SOLVED] Sand Snakes Level Problem (Python)

Level Help
1

Hey! I’m really stuck with this level. Here is my code:

loop:
    coins = self.findItems()
    coinIndex = 0
    nearest = None
    nearestDistance = 9999
    
    while coinIndex < len(coins):
        coin = coins[coinIndex]
        coinIndex += 1
        distance = self.distanceTo(coin)
 
    if distance < nearestDistance:
        nearest = coin
        nearestDistance = distance
    if nearest:
        self.moveXY(nearest.pos.x, nearest.pos.y)

My hero just runs into the mine. That’s the problem?

2

Hello @Vollut and welcome to the forums! Feel free to reuse existing topics (related to this level) to ask your question next time.

What your code currently does is that it goes through the list of coins and calculates their distance. Once that is finished(!), it compares distance with nearestDistance. However, at this point distance holds the value of the distance of the last coin…

So what do you need to fix it?

You should check the distance inside the while block, so you check it for every coin, not only the last one…

loop:
# define variables
    while ...
        # get coin distance
        if distance < nearestDistance:
            # set nearestCoin and nearestDistance
    if nearest:
        # move to coin
2 Likes
3

Oh, now I get it! Thank you! Now it works

1 Like
4

How does this not work.

while True:
    coins = hero.findItems()
    coinIndex = 0
    nearest = None
    nearestDistance = 9999
    # Loop through all the coins to find the nearest one.
    while coinIndex < len(coins):
        coin = coins[coinIndex]
        coinIndex += 1
        distance = hero.distanceTo(coin)
        # If this coin's distance is less than the nearestDistance
        if coin.distance < nearestDistance:
            
            # Set nearest to coin
            nearest = coin
            # Set nearestDistance to distance
            nearestDistance = distance
            hero.moveXY(nearest.pos.x, nearest.pos.y)
    # If there's a nearest coin, move to its position. You'll need moveXY so you don't cut corners and hit a trap
    hero.moveXY(nearest.pos.x, nearest.pos.y)
5

First, the line after nearestDistance = distance shouldn’t be there. You’re telling your hero to move twice.

You’ve defined the variable, “nearest,” but you’re not checking to see if nearest: before trying to move there. You should always check to make sure that an object exists before acting on the object. In this case it should work because nearest always exists but don’t count on that. Just get in the habit of putting if statements first.

if object:
    do something with object
6 
# This field is covered in firetraps.  Thankfully we've sent a scout ahead to find a path.  He left coins along the path so that if we always stick to the nearest coin, we'll avoid the traps.

# This canyon seems to interfere with your findNearest glasses!
# You'll need to find the nearest coins on your own.
while True:
    coins = hero.findItems()
    coinIndex = 0
    nearest = None
    nearestDistance = 9999
    
    # Loop through all the coins to find the nearest one.
    while coinIndex < len(coins):
        coin = coins[coinIndex]
        coinIndex += 1
        distance = hero.distanceTo(coin)
        # If this coin's distance is less than the nearestDistance
        if coin.distance < nearestDistance:
            # Set nearest to coin
            nearest = coin
            # Set nearestDistance to distance
            nearestDistance = distance
            
            # If there's a nearest coin, move to its position. You'll need moveXY so you don't cut corners and hit a trap.
    if nearest:
        hero.moveXY(nearest.pos.x, nearest.pos.y)

help please…

7

What’s coin.distance? Why don’t you use the variable you just defined on the line above.
When you set a variable like you did there: distance = hero.distanceTo(coin) It doesn’t become a property of coin, like coin.distance, instead it’s completely separate from the “coin”.
Danny

8

Thank you! I finished it.

9

while True:
coins = hero.findItems()
coinIndex = 0
nearest = None
nearestDistance = 9999

# Loop through all the coins to find the nearest one.
while coinIndex < len(coins):
    coin = coins[coinIndex]
    coinIndex += 1
    distance = hero.distanceTo(coin)
    # If this coin's distance is less than the nearestDistance
    if coin.distance < nearestDistance:
        coin.distance = nearestDistance
        nearest = coin
        # Set nearestDistance to distance
        nearestDistance = distance
        
        # If there's a nearest coin, move to its position. You'll need moveXY so you don't cut corners and hit a trap.
if nearest:
    hero.moveXY(nearest.pos.x, nearest.pos.y)

What am I doing wrong?

10

Hi @HatKid22, welcome to the forum. Your code is not fully formatted.
Please read this topic to learn how to format your code:

Thanks
Danny

11

if coin.distance < nearestDistance:
coin.distance does not exist, try using something else.

Luna