Plan a bisect when test runs differ in cost

A bisecting agent hunts for the commit that broke a test. Testing a commit means building it first, and builds take very different times: some hit the cache, some rebuild everything. You want the plan whose worst case finishes soonest.

Write bisect_plan(minutes) that returns the worst-case minutes of the best plan and the commit that plan tests first.

Input and output:

• minutes: 1 to 150 whole numbers from 0 to 1,000,000. Commits are listed oldest first, and testing commit i takes minutes[i].
• Return [worst, first]. worst is the smallest possible worst-case total. first is the index of the commit tested first by a plan with that worst case. If several commits could come first in such a plan, return the smallest index. When no test is needed, return [0, -1].

Rules:

• The commit just before commit 0 is good and the last commit is bad. Exactly one commit is the first bad one, and every commit after it is bad too.
• A test of commit i tells whether i is good or bad, and is never wrong.
• The plan chooses each test from the results so far. It stops once only one commit can be the first bad one.
• A plan's worst case is its largest total test time over every possible first bad commit.