good good study, day day up
Range of int in Cpp is - 2,147,483,648 to 2,147,483,647, use ( max - min ) / 2 + min instead of ( max + min ) / 2
Thus, abs(-2147483648) not defined
When doing pow, consider -1 && 1 seperately
When using binary search, always perform operations on tmp value
vector(nums.begin(), nums.begin() + length);