Greedy Algorithms · Coding problem
Lemonade Change
A free coding problem from the Greedy Denomination Coins skill. Read it here, then solve it in the app in Java or Python.
- Easy
- Coding problem
- Free
- Java and Python
The problem
A lemonade stand charges $5 a cup. Customers come one at a time, each paying with a single $5, $10 or $20 bill. The stand starts with no cash and has to hand back exact change from the bills it has collected so far. Return whether every customer gets their change.
Input format
n
<n bills>
Example
Input:
6
5 5 10 5 20 10
Output: true
The $20 gets a $10 and a $5 back, and the last $10 gets the remaining $5. With 5 10 10, the third customer can't be paid back: the only $5 already went to the second.
Constraints
1 <= n <= 10^5- Every bill is 5, 10 or 20
How it's graded
- Run checks your code against the examples. Submit also runs a hidden suite in four groups - basic cases, edge cases, random inputs and performance tests at the size limit - and shows which groups pass, never the hidden inputs.
- Stuck? Hints come in four steps, from a nudge to a code skeleton, each costing part of the points.
- Once you pass, you see the approaches from brute force to optimal, and where your solution lands among them.
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