문제
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).
제약 조건
2 ≤ length of text ≤ 100,000
At most 10,000 pairs; every value and the sum fit in a 64-bit integer
예시
입력:
text = "{\"apples\": 3, \"pears\": 5}"
예상 출력:
expected = 8입력:
std::string text = "{\"apples\": 3, \"pears\": 5}";
예상 출력:
long long expected = 8;입력:
string text = "{\"apples\": 3, \"pears\": 5}";
예상 출력:
long expected = 8;설명
3 + 5 = 8.
입력:
text = "{ \"debt\" : -20 , \"cash\":15 }"
예상 출력:
expected = -5입력:
std::string text = "{ \"debt\" : -20 , \"cash\":15 }";
예상 출력:
long long expected = -5;입력:
string text = "{ \"debt\" : -20 , \"cash\":15 }";
예상 출력:
long expected = -5;설명
Spaces around the symbols do not matter: −20 + 15 = −5.
접근 방법
먼저 스스로 풀어 본 뒤 힌트를 하나씩 열어 보세요.
힌트 1
Remove the braces, then split the pairs at commas.
힌트 2
Each value is the text after the colon; trim spaces before converting.
힌트 3
Use a 64-bit integer and return 0 for an empty object.
예상 복잡도
O(length of text) time, O(1) extra space
참고 자료
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