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Easy and Medium

Easy

Mixed warm-up set

Problem

A warm-up mixed set. Approach every problem the same way: understand the statement, find the pattern (hashing, two pointers, math…), reason about time/space, then implement and test on the examples.

In simple words

Warm-up problems: spot the pattern, then code it.

The idea

A mixed bag with no single technique. Work each one the same way: identify what is being asked, look for a familiar shape — a frequency count, two pointers, a running total, a sort — and only then reach for the code.

The trick

  • Most easy problems are one of four things: counting, sorting, scanning with a running value, or a hash lookup.
  • If a nested loop repeats a computation, precomputing it usually collapses the complexity.

This one walks through the worked example rather than tracing the algorithm frame by frame — a full walkthrough is still to be drawn. The code and the idea below are the real solution.

2
7
11
0
1
2

Step 1 of 2. Here's the example — nums = [2, 7, 11], target = 9 Values: 2, 7, 11.

1/2
Optimal
time—space—
1// general problem-solving loop2understand -> brute force -> spot the pattern3-> optimise -> test on examples

Input

array
[2, 7, 11]

Output

answer
—

Check yourself

1 quick question about this walkthrough. A wrong answer costs nothing.

Example

Input:
nums = [2, 7, 11], target = 9
Output:
[0, 1]
Explanation:
The easy version tries every pair. The medium version remembers what it has seen, and that single change is the whole step up in difficulty.

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