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add output for max_product algorithm
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#Given an integer array nums, find a contiguous non-empty subarray within the array that has the largest product, and return the product.
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#It is guaranteed that the answer will fit in a 32-bit integer.
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#A subarray is a contiguous subsequence of the array.
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#Example 1:
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#Input: nums = [2,3,-2,4]
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#Output: 6
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#Explanation: [2,3] has the largest product 6.
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# Given an integer array nums, find a contiguous non-empty subarray within the array that has the largest product, and return the product.
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# It is guaranteed that the answer will fit in a 32-bit integer.
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# A subarray is a contiguous subsequence of the array.
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#Example 2:
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#Input: nums = [-2,0,-1]
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#Output: 0
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#Explanation: The result cannot be 2, because [-2,-1] is not a subarray.
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# Example 1:
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# Input: nums = [2,3,-2,4]
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# Output: 6
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# Explanation: [2,3] has the largest product 6.
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#Constraints:
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#1 <= nums.length <= 2 * 104
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# Example 2:
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# Input: nums = [-2,0,-1]
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# Output: 0
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# Explanation: The result cannot be 2, because [-2,-1] is not a subarray.
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# Constraints:
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# 1 <= nums.length <= 2 * 104
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#-10 <= nums[i] <= 10
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#The product of any prefix or suffix of nums is guaranteed to fit in a 32-bit integer.
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#Dynamic Programming Approach (Kadane's Algorithm) - O(n) Time / O(1) Space
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#Track both current minimum and current maximum (Due to possibility of multiple negative numbers)
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#Answer is the highest value of current maximum
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# The product of any prefix or suffix of nums is guaranteed to fit in a 32-bit integer.
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# Dynamic Programming Approach (Kadane's Algorithm) - O(n) Time / O(1) Space
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# Track both current minimum and current maximum (Due to possibility of multiple negative numbers)
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# Answer is the highest value of current maximum
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# @param {Integer[]} nums
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# @return {Integer}
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def max_product(nums)
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return nums[0] if nums.length == 1
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return nums[0] if nums.length == 1
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cur_min, cur_max, max = 1, 1, -11
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cur_min = 1
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cur_max = 1
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max = -11
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nums.each do |val|
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tmp_cur_max = cur_max
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cur_max = [val, val*cur_max, val*cur_min].max
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cur_min = [val, val*tmp_cur_max, val*cur_min].min
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nums.each do |val|
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tmp_cur_max = cur_max
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cur_max = [val, val * cur_max, val * cur_min].max
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cur_min = [val, val * tmp_cur_max, val * cur_min].min
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max = [max, cur_max].max
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end
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max = [max, cur_max].max
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end
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max
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max
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end
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nums = [2, 3, -2, 4]
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puts max_product(nums)
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# Output: 6
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nums = [-2, 0, -1]
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puts max_product(nums)
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# Output: 0
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