Where I can see Equals(sol) source?
I'm tried round, floor, ceil, trunc with 1e-6 precision (and -7 and -5) and I can't pass the first test.
All tests on my desktop are passed when I compare like abs(res - expected) < 1e-6.
Or which function did you use for truncating?
std::floor(res * 1e6) / 1e6 - didn't work. (round, trunc, ceil)
Don't understand, how some people passed this.

going_Tests
Fixed__Tests
Log
1.275
1.2125
1.173214
1.146651
✘ Expected: equal to 1.14665 Actual: 1.14665

Random_tests
Log
****************** Random Tests **** going
1.071828
1.055739
1.077427
1.038521
1.052786
1.173214
1.032292
1.101158
✘ Expected: equal to 1.10116 Actual: 1.10116
I think this is some issues in Equals function

if (s1.empty() || s2.empty())
return true;

why this check is true always? according to the task - "AA","" is false, isn't it? but "z1","" is true.