Sum of Subarray Ranges — LeetCode 2104 Python Solution

The problem

You are given an integer array nums. The range of a subarray of nums is the difference between the largest and smallest element in the subarray.

Example

Input

nums = [1,2,3]

Output

4

Explanation

The 6 subarrays of nums are the following:

Python solution

class Solution:
    def subArrayRanges(self, nums: List[int]) -> int:
        ans, n = 0, len(nums)
        for i in range(n - 1):
            mi = mx = nums[i]
            for j in range(i + 1, n):
                mi = min(mi, nums[j])
                mx = max(mx, nums[j])
                ans += mx - mi
        return ans

Complexity

Pattern: Stack

When the most recent unresolved thing is the one that matters, use a stack. LeetCode 2104. Sum of Subarray Ranges is filed here because LeetCode tags it Stack, which is the vocabulary this hub collects.

The stack guide has the Python template for the pattern and the 194 LeetCode problems that use it.

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