Product of Array Except Self at Google — Interview Guide

• output[i] = (product of everything left of i) × (product of everything right of i).
• First pass left-to-right accumulates the running left product.
• Second pass right-to-left multiplies in the running right product.

def product_except_self(nums):
    res = [1] * len(nums)
    left = 1
    for i in range(len(nums)):
        res[i] = left
        left *= nums[i]
    right = 1
    for i in range(len(nums) - 1, -1, -1):
        res[i] *= right
        right *= nums[i]
    return res

• Algorithmic fluency — the right data structure and the optimal complexity, fast.
• Googleyness — comfort with ambiguity, intellectual curiosity, and a collaborative style.
• Leadership and impact — especially at L4+; evidence of driving outcomes.
• Communication — explaining your thinking as you solve.