leetcode 1508. Range Sum of Sorted Subarray Sums(python)

278 阅读1分钟

描述

Given the array nums consisting of n positive integers. You computed the sum of all non-empty continous subarrays from the array and then sort them in non-decreasing order, creating a new array of n * (n + 1) / 2 numbers.

Return the sum of the numbers from index left to index right (indexed from 1), inclusive, in the new array. Since the answer can be a huge number return it modulo 10^9 + 7.

Example 1:

Input: nums = [1,2,3,4], n = 4, left = 1, right = 5
Output: 13 
Explanation: All subarray sums are 1, 3, 6, 10, 2, 5, 9, 3, 7, 4. After sorting them in non-decreasing order we have the new array [1, 2, 3, 3, 4, 5, 6, 7, 9, 10]. The sum of the numbers from index le = 1 to ri = 5 is 1 + 2 + 3 + 3 + 4 = 13. 

Example 2:

Input: nums = [1,2,3,4], n = 4, left = 3, right = 4
Output: 6
Explanation: The given array is the same as example 1. We have the new array [1, 2, 3, 3, 4, 5, 6, 7, 9, 10]. The sum of the numbers from index le = 3 to ri = 4 is 3 + 3 = 6.

Example 3:

Input: nums = [1,2,3,4], n = 4, left = 1, right = 10
Output: 50

Note:

1 <= nums.length <= 10^3
nums.length == n
1 <= nums[i] <= 100
1 <= left <= right <= n * (n + 1) / 2

解析

根据题意,最暴利的解法就是将 nums 的子数组和都算出来放入 res 中,然后对 res 进行排序,最后将 res[left-1:right] 的子数组求和并对 10**9+7 取模即可,只是这种方法太没技术含量了,鄙视自己的投机取巧。

解答

class Solution(object):
    def rangeSum(self, nums, n, left, right):
        """
        :type nums: List[int]
        :type n: int
        :type left: int
        :type right: int
        :rtype: int
        """
        res = []
        for i in range(n):
            for j in range(i+1, n+1):
                res.append(sum(nums[i:j]))
        res.sort()
        return sum(res[left-1:right])%(10**9+7)
            	      
			

运行结果

Runtime: 5696 ms, faster than 10.53% of Python online submissions for Range Sum of Sorted Subarray Sums.
Memory Usage: 33.7 MB, less than 36.84% of Pyt

原题链接:leetcode.com/problems/ra…

您的支持是我最大的动力