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Given a list of integers, write a Python function to return the number of unique pairs that sum up to a target.

Python/Codingeasy0.1 min readPremium
Frequency
Low
Asked at 1 company
Category
179
questions in Python/Coding
Difficulty Split
127E|24M|28H
in this category
Total Bank
1,863
across 7 categories
Asked at these companies
Amazon
Key Concepts Tested
python
Expert AnswerPremium
23 wordsInterview-ready
**Unique pairs:** seen=set(); for x: if target-x in seen and 2*x!=target: count+=1; seen.add(x). **Duplicates:** Counter; count min(c[x],c[target-x]) for x<target/2. O(n). **Why:** One pass.
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