Problem
Data typed by people is messy. You get a list of strings and must add up the ones that are whole numbers, ignoring the rest instead of crashing.
An entry counts if, after removing spaces at both ends, it is an optional + or - sign followed by one or more digits. Anything else (empty text, decimals such as "2.5", words) is skipped.
Implement sum_valid_numbers(values).
Input
values: The entries to read.
Output
Return the sum of the valid whole numbers (0 if there are none).
Constraints
0 ≤ number of entries ≤ 1,000
Each entry has at most 20 characters; valid numbers fit in a 64-bit integer
Examples
Input:
values = ["10", " 5 ", "abc", "-3"]
Expected output:
expected = 12Input:
std::vector<std::string> values = {"10", " 5 ", "abc", "-3"};
Expected output:
long long expected = 12;Input:
string[] values = new string[] {"10", " 5 ", "abc", "-3"};
Expected output:
long expected = 12;Explanation
"10", " 5 " (spaces are trimmed) and "-3" are whole numbers; "abc" is skipped. 10 + 5 - 3 = 12.
Input:
values = ["2.5", "", "seven"]
Expected output:
expected = 0Input:
std::vector<std::string> values = {"2.5", "", "seven"};
Expected output:
long long expected = 0;Input:
string[] values = new string[] {"2.5", "", "seven"};
Expected output:
long expected = 0;Explanation
None of the entries is a whole number, so the sum is 0.
How to approach it
Try on your own first, then open one hint at a time.
Hint 1
Strip the spaces first, then decide whether what is left is a valid whole number.
Hint 2
Converting inside try/except (or checking the characters) lets you skip bad entries without stopping.
Hint 3
Remember that a lone sign such as "+" is not a number.
Expected complexity
O(total length) time, O(1) extra space
References
This challenge is adapted for CodeUtility. Follow the statement and constraints above.