1. 程式人生 > 其它 >啊啊 啊 好久沒寫了 我發現一件事情一懶 件件事情都會變懶。元旦前把這一年的結了吧 107 - 113 還送個103?

啊啊 啊 好久沒寫了 我發現一件事情一懶 件件事情都會變懶。元旦前把這一年的結了吧 107 - 113 還送個103?

題目如下:

You are given an integer arraynumssorted innon-decreasingorder.

Build and returnan integer arrayresultwith the same length asnumssuch thatresult[i]is equal to thesummation of absolute differencesbetweennums[i]and all the other elements in the array.

In other words,result[i]is equal tosum(|nums[i]-nums[j]|)

where0 <= j < nums.lengthandj != i(0-indexed).

Example 1:

Input: nums = [2,3,5]
Output: [4,3,5]
Explanation: Assuming the arrays are 0-indexed, then
result[0] = |2-2| + |2-3| + |2-5| = 0 + 1 + 3 = 4,
result[1] = |3-2| + |3-3| + |3-5| = 1 + 0 + 2 = 3,
result[2] = |5-2| + |5-3| + |5-5| = 3 + 2 + 0 = 5.

Example 2:

Input: nums = [1,4,6,8,10]
Output: [24,15,13,15,21]

Constraints:

  • 2 <= nums.length <= 105
  • 1 <= nums[i] <= nums[i + 1] <= 104

解題思路:對於nums[i],我們很容易可以求出0~i-1區間和total_left以及i+1~nums.length-1的區間和total_right,那麼對於左半部分的sum有:i*nums[i] - total_left,右半部分有:total_right - (len(nums) - i - 1)*nums[i]。

程式碼如下:

class Solution(object):
    def getSumAbsoluteDifferences(self, nums):
        """
        :type nums: List[int]
        :rtype: List[int]
        """
        total = []
        count = 0
        for i in nums:
            count += i
            total.append(count)

        res = []
        for i in range(0,len(nums)):
            left = right = 0
            if i > 0:
                left = i*nums[i] - total[i-1]
            if i < len(nums) - 1:
                right = (total[-1] - total[i]) - (len(nums) - i - 1)*nums[i]
            res.append(left + right)
        return res