Leetcode:241. Different Ways to Add Parentheses

Description

解题思路

本题为分治算法问题，题意为给定一串数字和操作符，进行计算，返回所有可能结果。代码如下

class Solution {
public:
    vector<int> diffWaysToCompute(string input) {
        vector<int> result;
        int size = input.size();
        for (int i = 0; i < size; i++) {
            char cur = input[i];
            if (cur == '+' || cur == '-' || cur == '*') {
                // 将输入字符串分成两部分，分别递归求解
                vector<int> result1 = diffWaysToCompute(input.substr(0, i));
                vector<int> result2 = diffWaysToCompute(input.substr(i+1));
                for (auto n1 : result1) {
                    for (auto n2 : result2) {
                        if (cur == '+')
                            result.push_back(n1 + n2);
                        else if (cur == '-')
                            result.push_back(n1 - n2);
                        else
                            result.push_back(n1 * n2);    
                    }
                }
            }
        }
        // if the input string contains only number
        if (result.empty())
            result.push_back(atoi(input.c_str()));
        return result;
    }
};