<p>Given a string <code>expression</code> of numbers and operators, return <em>all possible results from computing all the different possible ways to group numbers and operators</em>. You may return the answer in <strong>any order</strong>.</p>

<p>The test cases are generated such that the output values fit in a 32-bit integer and the number of different results does not exceed <code>10<sup>4</sup></code>.</p>

<p>&nbsp;</p>
<p><strong class="example">Example 1:</strong></p>

<pre>
<strong>Input:</strong> expression = &quot;2-1-1&quot;
<strong>Output:</strong> [0,2]
<strong>Explanation:</strong>
((2-1)-1) = 0 
(2-(1-1)) = 2
</pre>

<p><strong class="example">Example 2:</strong></p>

<pre>
<strong>Input:</strong> expression = &quot;2*3-4*5&quot;
<strong>Output:</strong> [-34,-14,-10,-10,10]
<strong>Explanation:</strong>
(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
</pre>

<p>&nbsp;</p>
<p><strong>Constraints:</strong></p>

<ul>
	<li><code>1 &lt;= expression.length &lt;= 20</code></li>
	<li><code>expression</code> consists of digits and the operator <code>&#39;+&#39;</code>, <code>&#39;-&#39;</code>, and <code>&#39;*&#39;</code>.</li>
	<li>All the integer values in the input expression are in the range <code>[0, 99]</code>.</li>
</ul>

class Solution {
public:
    vector<int> f(int i,int j,string expression){
        vector<int> vec;
        if(i>j){
            return vec;
        }
        if(i==j){
            string str;
            str+=expression[i];
            vec.push_back(stoi(str));
            return vec;
        }
        if(i+1==j){
            string str;
            str+=expression[i];
            str+=expression[j];
            vec.push_back(stoi(str));
            return vec;
        }
        for(int ptr=i;ptr<=j;ptr++){
            vector<int> left,right;
            if(expression[ptr]=='+' ||expression[ptr]=='*'||expression[ptr]=='-'){
                vector<int> left=f(i,ptr-1,expression);
                vector<int> right=f(ptr+1,j,expression);
                for(auto val1:left){
                    for(auto val2:right){
                        if(expression[ptr]=='+'){
                            vec.push_back(val1+val2);
                        }
                        else if(expression[ptr]=='*'){
                            vec.push_back(val1*val2);
                        }
                        else if(expression[ptr]=='-'){
                            vec.push_back(val1-val2);
                        }
                    }
                }
            }
        }
        return vec;
    }
    vector<int> diffWaysToCompute(string expression) {
        return f(0,expression.size()-1,expression);
    }
};
15000