[leetcode 241]Different Ways to Add Parentheses

Given a string of numbers and operators, return all possible results from computing all the different possible ways to group numbers and operators. The valid operators are+, - and *.

Example 1

Input: "2-1-1".

((2-1)-1) = 0
(2-(1-1)) = 2

Output: [0, 2]

Example 2

Input: "2*3-4*5"

(2*(3-(4*5))) = -34
((2*3)-(4*5)) = -14
((2*(3-4))*5) = -10
(2*((3-4)*5)) = -10
(((2*3)-4)*5) = 10

Output: [-34, -14, -10, -10, 10]

给定一个字符串含有数字字符和+、-、*（没说有没有空格，就当有空格处理）

代码一多，就有点乱，思路大体是：

1、将输入字符串依照数字和运算符号分离，按顺序分别存入两个vector;

2、使用二维的vector作为标记，vector[i][j]表示字符串i到j的运算结果。由于运算结果可能有多个还有可能反复所以使用multiset

3、动态的计算vector[i][j]，知道得到结果vector[0][input.size()-1];

AC代码：

class Solution
{
public:
    vector<int> diffWaysToCompute(string input)
    {
        int sum=0;
        vector<int> num;
        vector<char> sign;
        int len=input.size();
        int x=0;
        int y=0;
        vector<int> res;
        while(x<len)
        {
            if(input[x]>='0'&&input[x]<='9')
            {
                y=0;
                while(x<len&&input[x]>='0'&&input[x]<='9')
                {
                    y=y*10+input[x]-48;
                    ++x;
                }
                num.push_back(y);
                ++sum;
            }
            else if(input[x]==' ')
                ++x;
            else
            {
                sign.push_back(input[x]);
                ++x;
            }
        }
        vector<vector<multiset<int> > > temp;
        multiset<int> temp_set;
        vector<multiset<int> >temp_vec;
        for(int i=0; i<sum; ++i)
            temp_vec.push_back(temp_set);
        for(int i=0; i<sum; ++i)
            temp.push_back(temp_vec);
        for(int i=0; i<sum; ++i)
            temp[i][i].insert(num[i]);
        for(int i=1; i<sum; ++i)
        {
            if(sign[i-1]=='+')
                temp[i-1][i].insert(num[i-1]+num[i]);
            else if(sign[i-1]=='-')
                temp[i-1][i].insert(num[i-1]-num[i]);
            else
                temp[i-1][i].insert(num[i-1]*num[i]);
        }
        for(int i=2; i<sum; ++i)
        {
            for(int j=0; j+i<sum; ++j)
            {
                multiset<int>::iterator ite=temp[j][j].begin();
                for(multiset<int>::iterator ite2=temp[j+1][i+j].begin(); ite2!=temp[j+1][i+j].end(); ++ite2)
                {
                    if(sign[j]=='+')
                        temp[j][i+j].insert(*ite+(*ite2));
                    else if(sign[j]=='-')
                        temp[j][i+j].insert(*ite-(*ite2));
                    else
                        temp[j][i+j].insert(*ite*(*ite2));
                    }
                ite=temp[i+j][i+j].begin();
                for(multiset<int>::iterator ite2=temp[j][i+j-1].begin(); ite2!=temp[j][i+j-1].end(); ++ite2)
                {
                    if(sign[i+j-1]=='+')
                        temp[j][i+j].insert(*ite2+(*ite));
                    else if(sign[j+i-1]=='-')
                        temp[j][i+j].insert(*ite2-(*ite));
                    else
                        temp[j][i+j].insert(*ite2*(*ite));
                    }
                for(int k=j+1; k<i+j-1; ++k)
                {
                    for(multiset<int>::iterator ite2=temp[j][k].begin(); ite2!=temp[j][k].end(); ++ite2)
                    {
                        for(multiset<int>::iterator ite3=temp[k+1][j+i].begin(); ite3!=temp[k+1][j+i].end(); ++ite3)
                        {
                            if(sign[k]=='+')
                                temp[j][i+j].insert(*ite2+(*ite3));
                            else if(sign[k]=='-')
                                temp[j][i+j].insert(*ite2-(*ite3));
                            else
                                temp[j][i+j].insert(*ite2*(*ite3));
                            }
                    }
                }
            }
        }
        for(multiset<int>::iterator ite2=temp[0][sum-1].begin();ite2!=temp[0][sum-1].end();++ite2)
            res.push_back(*ite2);
        return res;
    }
};

其它Leetcode题目AC代码：https://github.com/PoughER/leetcode