Target Sum
Given an array of integers and a target sum Assign + or - to each number to reach the target Return the number of different ways to achieve this Example: nums = [1,1,1,1,1], target = 3 => 5 ways (+1+1+1+1+1 = 5, +1+1+1-1-1 = 1, etc.)
Target Sum is a dynamic programming question: define the state cleanly and the transitions usually follow. Interviewers love it because it reveals your state-and-transition thinking and your edge-case discipline. Don't rush the code—spend your time nailing the state definition first.
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