Give it an input and say what you think comes back. It compiles and runs for real, so a wrong guess still shows you the answer — probe as much as you like. Only correct predictions count.
Locked until you have predicted 3 outputs correctly.
| 1 | void build(int open, int close, string& current, |
| 2 | vector<string>& out) { |
| 3 | if (open == 0 && close == 0) { |
| 4 | out.push_back(current); |
| 5 | return; |
| 6 | } |
| 7 | |
| 8 | if (open > 0) { |
| 9 | current.push_back('('); |
| 10 | build(open - 1, close + 1, current, out); |
| 11 | current.pop_back(); |
| 12 | } |
| 13 | if (close > 0) { |
| 14 | current.push_back(')'); |
| 15 | build(open, close - 1, current, out); |
| 16 | current.pop_back(); |
| 17 | } |
| 18 | } |
| 19 | |
| 20 | vector<string> solution(int n) { |
| 21 | vector<string> out; |
| 22 | string current; |
| 23 | build(n, 0, current, out); |
| 24 | return out; |
| 25 | } |
Names have been stripped. The signature is the only clue you get for free. Compiled as C++20 with the standard headers and using namespace std; already in scope.