Fantastic. I was trying to create this simple O(n) O(n) solution. Only when you see it do you realise how simple it is. Kicking myself, as I was almost there twice but deleted and went down other avenues.
Great work.

Doesnt this solution conduct two passes? - one for splitting, and one for finding the min? So for larger strings this would be less efficient than a single for loop.

its a c++17 feature, so is more efficient. eg for larger vector sizes. It can run both accumulation and reduction in parrallel meaning its optimized for multicore systems. Although for this eg the differences are miniscule.

agree.

Why is this answer getting so many best practice votes? Surely since sqrt returns a floating point value, with which arithmatic is limited in precision, which could cause false answers. It would also risk undefined behaviour due to integer overflow with larger n values as squaresquare (square_rootsquare_root) reaches the max value for an int.
Calculating square roots is also much slower than other integer operations so its not really an efficient approach. Am i mistaken here or missing something?