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Finding Minimum scalar product of two vectors

Learn how to solve the 'Finding Minimum scalar product of two vectors' problem. This detailed resource details brute force and optimized approaches.

Problem Statement

Easy

Write a function min_scalar_product(v1, v2) that takes two lists of integers of equal length and returns the minimum possible scalar (dot) product. You can rearrange elements in both vectors in any order before computing the dot product. The dot product is sum(v1[i] * v2[i]) for all i. To minimize, pair the largest of one with the smallest of the other.

Constraints
  • 1 <= len(v1) == len(v2) <= 10^4
  • -10^5 <= v1[i], v2[i] <= 10^5

Examples

Example 1
Input
v1 = [1, 3, -5], v2 = [-2, 4, 1]
Output
-25
Explanation

Sort v1 ascending: [-5,1,3]. Sort v2 descending: [4,1,-2]. Dot product: (-5)*4 + 1*1 + 3*(-2) = -20+1-6 = -25.

Example 2
Input
v1 = [1, 2, 3], v2 = [4, 5, 6]
Output
32
Explanation

Sort v1 ascending: [1,2,3]. Sort v2 descending: [6,5,4]. Dot: 1*6+2*5+3*4 = 6+10+12 = 32? Wait: minimum is 1*6+2*5+3*4=32. Alternative: 1*4+2*5+3*6=32. Actually min is 1*6+2*5+3*4=32.

Example 3
Input
v1 = [1, 1], v2 = [1, 1]
Output
2
Explanation

Both vectors are [1,1]. Any arrangement gives 1*1 + 1*1 = 2.

Need a Hint?
Use simple arithmetic operators (like modulo `%`, division `//`), conditional checks, or loops to inspect number properties.
Edge Cases to Watch
  • Empty list or null input variables
  • Single item lists/arrays
  • Extremely large input bounds causing integer or stack overflow

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