Problem
Programs often receive JSON such as {"apples": 3, "pears": 5}. Libraries like System.Text.Json parse it for you, but parsing a simple case by hand shows how the format works.
The input is a flat JSON object: {, then zero or more "key": value pairs separated by commas, then }. Keys are quoted and contain no quotes, commas or colons; values are integers, possibly negative. Spaces may appear around any of the symbols.
Implement sum_json_numbers(text).
Input
text: The JSON object.
Output
Return the sum of all values (0 for an empty object).
Constraints
2 ≤ length of text ≤ 100,000
At most 10,000 pairs; every value and the sum fit in a 64-bit integer
Examples
Input:
text = "{\"apples\": 3, \"pears\": 5}"
Expected output:
expected = 8Input:
std::string text = "{\"apples\": 3, \"pears\": 5}";
Expected output:
long long expected = 8;Input:
string text = "{\"apples\": 3, \"pears\": 5}";
Expected output:
long expected = 8;Explanation
3 + 5 = 8.
Input:
text = "{ \"debt\" : -20 , \"cash\":15 }"
Expected output:
expected = -5Input:
std::string text = "{ \"debt\" : -20 , \"cash\":15 }";
Expected output:
long long expected = -5;Input:
string text = "{ \"debt\" : -20 , \"cash\":15 }";
Expected output:
long expected = -5;Explanation
Spaces around the symbols do not matter: −20 + 15 = −5.
How to approach it
Try on your own first, then open one hint at a time.
Hint 1
Remove the braces, then split the pairs at commas.
Hint 2
Each value is the text after the colon; trim spaces before converting.
Hint 3
Use a 64-bit integer and return 0 for an empty object.
Expected complexity
O(length of text) time, O(1) extra space
References
This challenge is adapted for CodeUtility. Follow the statement and constraints above.