Each position depends on all previous positions. But you don't need to recompute the entire sum each time. Notice that runningSum[i] = runningSum[i-] + nums[i]. You carry forward the previous sum and add the current element. You're using the prefix accumulation pattern. Store the cumulative result as you iterate left to right.
##### ###### ##### ### # # ### # # ###### ## ## ## ## ## ## ## # # # # # ## ##### #### ##### # # # # # # # #### ## # ## ## ## ## # # # # # ## ## # ###### ## ### # ### # ######
$ curl repovive.com/roadmaps/maang-interview-prep/arrays-hashing/running-sum-hint
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