Add Signed Character Arrays
ByteDance● MediumFULLTIMEPHONE SCREENProblem statement
Two signed decimal integers are stored in character arrays left and right. Each array contains an optional leading + or -, followed by one or more decimal digits.
Return their exact sum as a normalized character array:
- Do not use a fixed-width numeric conversion or arbitrary-precision integer library.
- Remove leading zeros from the magnitude.
- Use a leading
-only when the result is negative. - Represent zero exactly as
['0'].
Function
addSignedNumbers(left: char[], right: char[]) → char[]Examples
Example 1
left = ["-","1","2","3"]right = ["4","5"]return = ["-","7","8"]The operands are -123 and 45, whose sum is -78.
Example 2
left = ["9","9","9"]right = ["1"]return = ["1","0","0","0"]A carry propagates through all three digits, producing 1000.
Example 3
left = ["-","5","0"]right = ["+","5","0"]return = ["0"]Equal magnitudes with opposite signs cancel, and zero has no sign.
Constraints
1 <= left.length, right.length <= 200000- Each input has an optional leading sign followed by at least one decimal digit.
- Each input is a valid integer encoding; leading zeros are allowed.
- The total input size fits in memory.