leetcode

0 class Solution {

1 int operate(char op, int a, int b) {

2 switch (op) {

3 case '+': return a + b;

4 case '-': return a - b;

5 case '*': return a * b;

6 }

7 return 0;

8 }

9

10 vector<int> rec(const string &expression, int start, int end) {

11 vector<int> res;

12 for (int i = start; i < end; i++) {

13 if (isdigit(expression[i])) continue;

14 for (auto n1 : rec(expression, start, i))

15 for (auto n2 : rec(expression, i + 1, end))

16 res.push_back(operate(expression[i], n1, n2));

17 }

18 if (res.empty()) return {stoi(expression.substr(start, end - start))};

19 return res;

20 }

21

22 public:

23 vector<int> diffWaysToCompute(const string &expression) { return rec(expression, 0, expression.size()); }

24 };