Minimum sum

Computer Science Level 3

Given the following sum: $S = \sum_{i=1}^n a_i b_i \ \ \ where \ a_i \ ,\ b_i > 0$ $S$ is minimal when the two equences $[ a_1,a_2,\cdots,a_n]$ and $[b_1,b_2,\cdots,b_n]$

are sorted ---------------

can not be determined in creasing order in dereasing order the same way one increasing and one decreasing

1 solution

Hasmik Garyaka
Sep 21, 2017

One example. Let both sequences will be 1,2,3,4,5,...n If both are increasing, it will be sum of n^2. If one is increasing and one decreasing, it will be sum of n(n-i).

Minimum sum

1 solution

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