题目

different-ways-to-add-parentheses

2. 算法

* 直接模拟

3. 代码

class Solution {
public:
    vector<int> diffWaysToCompute(string input) {
        vector<int> res;
        for (int i = 0; i < input.size(); ++i) {
            if (input[i] == '+' || input[i] == '-' || input[i] == '*') {
                vector<int> left = diffWaysToCompute(input.substr(0, i));
                vector<int> right = diffWaysToCompute(input.substr(i + 1));
                for (int j = 0; j < left.size(); ++j) {
                    for (int k = 0; k < right.size(); ++k) {
                        if (input[i] == '+') res.push_back(left[j] + right[k]);
                        else if (input[i] == '-') res.push_back(left[j] - right[k]);
                        else res.push_back(left[j] * right[k]);
                    }
                }
            }
        }
        if (res.empty()) res.push_back(atoi(input.c_str()));
        return res;
    }
};