Arrays and linear scans

Implement Prototype(loads []int) Summary as a direct scan and Solve as one O(n) pass using O(1) summary state. Return Total and a pointer to the first maximum index. Nonnegative inputs; ties keep the smallest index. Empty input gives {0,nil} and [0] gives {0,&0}. Preserve input. All arithmetic fits int.

Edit exercise.go; retain the public types and signatures. prototype and final are separate stages. The executable tests recover panics as failures, report named checks, and exit nonzero on any failure. A successful run must execute at least one check. Tests use logical time or explicit synchronization where relevant.