Greedy Algorithms - Remove K Digits (Smallest Number)
Given the following code snippet implementing the optimal greedy solution to remove k digits, what is the output of
removeKdigits("1432219", 3)?Given the following code snippet implementing the optimal greedy solution to remove k digits, what is the output of removeKdigits("1432219", 3)?
easy🧾 Code Trace Q3 of Q15
Step-by-Step Solution
Solution:
Step 1: Trace stack operations for input "1432219", k=3
Remove digits '4', '3', and '2' greedily when a smaller digit appears.Step 2: Final builder after removals is ['1','2','1','9']
Joining and stripping zeros yields "1219".Final Answer:
Option D -> Option DQuick Check:
Matches known example output [OK]
Quick Trick: Greedy stack removes larger digits before smaller ones [OK]
Common Mistakes:
MISTAKES- Off-by-one removals
- Not removing enough digits
- Incorrect leading zero removal
Trap Explanation:
PITFALL- Candidates often forget to remove remaining digits if k > 0 after iteration, leading to wrong output.
Interviewer Note:
CONTEXT- Tests ability to mentally execute greedy stack code on typical input.
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