Asked in: Walmart
Image of the Question
All Testcases Passed ✔
Solution
n = int(input())
h = {}
flag = True
for i in range(n):
// ... rest of solution available after purchaseExplanation
```
To solve the problem of counting repeated game scores and identifying their indices, begin by carefully analyzing the input and output requirements, and then think through a systematic method to track the occurrences of each score efficiently.
Step 1: Understand the Input and Output
- Input consists of an integer N denoting the number of students.
- Then N integers follow, each representing a student's score.
- The task is to find all scores that appear more than once (duplicates).
- For each duplicated score, print the score itself, followed by the letter 'l' (or 'I' as indicated), and then the list of indices (positions) where the score occurs.
- Indices are typically zero-based or one-based; clarify from the problem statement which indexing to use. Usually, in such cases, zero-based indexing is common unless otherwise specified.
- If no duplicates exist, print -1.
Step 2: Data Structures to Use
- To efficiently find duplicates and record their indices, consider using a dictionary or hashmap structure.
- The key will be the score.
- The value will be a list of indices where the score appears.
- This allows efficient insertion and retrieval as you iterate through the scores.
Step 3: Iteration Over Scores
- Iterate through the list of scores from index 0 to N-1.
- For each score, append the current index to its corresponding list in the dictionary.
- If the score is not yet in the dictionary, create a new entry with a list containing the current index.
Step 4: Identify Duplicates
- After processing all scores, iterate through the dictionary entries.
- For each score, check the length of the list of indices.
- If the length is greater than 1, it indicates the score appeared multiple times.
- Collect these scores and their index lists for output.
Step 5: Formatting Output
- For each duplicate score, output the score followed by the letter 'l' and then the indices separated by spaces.
- Ensure to output the indices in the order they were recorded, which should naturally be the case if you appended them during the iteration.
- If no duplicates exist, output -1.
Step 6: Handling Edge Cases
- All scores could be unique, so output must be -1.
- All scores could be identical, so all indices should be listed.
- Scores can have varying values, positive or negative, but since problem statement does not specify otherwise, assume integer values including possibly zero.
- Confirm whether indices should be zero-based or one-based from problem statement; adjust output accordingly.
Step 7: Complexity and Efficiency
- This approach requires only a single pass through the scores array to build the dictionary.
- Then one pass through the dictionary keys to find duplicates.
- Overall time complexity is O(N), which is efficient for large inputs.
- Space complexity is O(N) for the dictionary to store indices.
Step 8: Summary
- Use a dictionary mapping each score to a list of its indices.
- Populate this dictionary in one pass.
- Identify all keys with multiple indices.
- Format output by printing score, letter 'l', and indices.
- If no duplicates found, print -1.
This method ensures the problem is solved cleanly and efficiently without unnecessary repeated traversals or complex data structures.
```