I don't understand why we use a hash map here instead of nested loops?
Great question! Nested loops would give us O(n²) time complexity - for 10,000 elements, that's 100 million operations. A hash map trades space for time, reducing this to O(n) - just 10,000 operations. Would you like me to show you how the hash map approach works step by step?
I'm stuck on this two-pointer problem. Can you give me a hint?
Think about what conditions determine when to move each pointer. In this sorted array problem, if the sum of elements at both pointers is too small, which pointer should move and why? Try thinking about this before I reveal more.
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