453. Minimum Moves to Equal Array Elements

Given an integer array nums of size n, return the minimum number of moves required to make all array elements equal.

In one move, you can increment n - 1 elements of the array by 1.

Example 1:

Input: nums = [1,2,3]
Output: 3
Explanation: Only three moves are needed (remember each move increments two elements):
[1,2,3]  =>  [2,3,3]  =>  [3,4,3]  =>  [4,4,4]

翻译

给定一个大小为size的数组nums,每次你需要对它的“除最大值以外”的值进行+1操作,当数组中所有值都一样时结束。问:经过多少次可以达到平衡

思路

我们先来观察一组数据:

数组 迭代次数
[1, 3, 7, 11] 0
[2, 4, 8, 11] 1
[3, 5, 9, 11] 2
[4, 6, 10, 11] 3
[5, 7, 11, 11] 4
[6, 8, 11, 12] 5
[7, 9, 12, 12] 6
[8, 10, 12, 13] 7
[9, 11, 13, 13] 8
[10, 12, 13, 14] 9
[11, 13, 14, 14] 10
[12, 14, 14, 15] 11
[13, 15, 15, 15] 12
[14, 15, 16, 16] 13
[15, 16, 16, 17] 14
[16, 17, 17, 17] 15
[17, 17, 18, 18] 16
[18, 18, 18, 19] 17
[19, 19, 19, 19] 18

通过观察这组数据,可以发现:

  • 经过 ( 11 − 7 ) × 1 = 4 (11-7) \times 1=4 (117)×1=4 次后,最后两位数可以达到平衡
  • 经过 ( 7 − 3 ) × 2 = 8 (7-3) \times 2 =8 (73)×2=8 次后,最后三位可以达到平衡,因为第二位每次加1,需要后两位交替2次
  • 经过 ( 3 − 1 ) × 3 = 6 (3-1)\times 3=6 (31)×3=6 次后,最后四位(全部)可以达到平衡,最后第第一位每加1,需要后面三位交替3次

经过总结,可以得到如下公式:

设  nums有序,且  nums = [ x 1 , x 2 , x 3 , ⋯   , x n ] \text{设~~nums有序,且~~nums} = [ x_1,x_2,x_3, \cdots , x_n]   nums有序,且  nums=[x1,x2,x3,,xn]

则,总次数为
T = ( x n − x n − 1 ) × 1 + ( x n − 1 − x n − 2 ) × 2 + ⋯ + ( x 2 − x 1 ) × ( n − 1 ) = x n + x n − 1 + … ⋯ + x 2 − x 1 ( n − 1 ) = x n + x n − 1 + … ⋯ + x 2 + x 1 − x 1 n \begin{aligned} \\\\ T&=(x_n-x_{n-1})\times 1 +(x_{n-1} - x_{n-2})\times2 + \cdots +(x_2-x_1)\times (n-1) \\\\ &= x_{n}+x_{n-1}+\ldots \cdots+x_{2}-x_{1}(n-1) \\\\ & =x_{n}+x_{n-1}+\ldots \cdots+x_{2} + x_1 - x_{1}n \end{aligned} T=(xnxn1)×1+(xn1xn2)×2++(x2x1)×(n1)=xn+xn1++x2x1(n1)=xn+xn1++x2+x1x1n

将测试数据代入该公式,为:
T = 11 + 7 + 3 + 1 − 1 × 4 = 18 T = 11+7+3 + 1 - 1\times 4 = 18 T=11+7+3+11×4=18

上代码
class Solution:
    def minMoves(self, nums) -> int:
		return sum(nums) - len(nums)*min(nums)