76. implement BigInt addition with sign
medium - accepted / - tried
This is a follow-up on 62. implement BigInt addition.
You are asked to implement a string addition function, with possible negative integers. Also, '+' plus sign should also be supported
add('-999999999999999999', '-1') // '-1000000000000000000' add('-999999999999999999', '+1') // '-999999999999999998'
Don't use BigInt directly, it is not our goal here.