<p>Given a string <code>num</code> that contains only digits and an integer <code>target</code>, return <em><strong>all possibilities</strong> to insert the binary operators </em><code>&#39;+&#39;</code><em>, </em><code>&#39;-&#39;</code><em>, and/or </em><code>&#39;*&#39;</code><em> between the digits of </em><code>num</code><em> so that the resultant expression evaluates to the </em><code>target</code><em> value</em>.</p>

<p>Note that operands in the returned expressions <strong>should not</strong> contain leading zeros.</p>

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

<pre>
<strong>Input:</strong> num = &quot;123&quot;, target = 6
<strong>Output:</strong> [&quot;1*2*3&quot;,&quot;1+2+3&quot;]
<strong>Explanation:</strong> Both &quot;1*2*3&quot; and &quot;1+2+3&quot; evaluate to 6.
</pre>

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

<pre>
<strong>Input:</strong> num = &quot;232&quot;, target = 8
<strong>Output:</strong> [&quot;2*3+2&quot;,&quot;2+3*2&quot;]
<strong>Explanation:</strong> Both &quot;2*3+2&quot; and &quot;2+3*2&quot; evaluate to 8.
</pre>

<p><strong class="example">Example 3:</strong></p>

<pre>
<strong>Input:</strong> num = &quot;3456237490&quot;, target = 9191
<strong>Output:</strong> []
<strong>Explanation:</strong> There are no expressions that can be created from &quot;3456237490&quot; to evaluate to 9191.
</pre>

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

<ul>
	<li><code>1 &lt;= num.length &lt;= 10</code></li>
	<li><code>num</code> consists of only digits.</li>
	<li><code>-2<sup>31</sup> &lt;= target &lt;= 2<sup>31</sup> - 1</code></li>
</ul>

class Solution {
public:
vector<string>sa;
string s;
    
   void help(string num,int target,int i,long long prev,long long cur){
    if(i==num.size()){
        if(cur==target){
            sa.push_back(s);
        }
        return;
    }
    for(int start=i;start<num.size();start++){
       if (start!=i && num[i] == '0') {
            break;
        }
        string part=num.substr(i,start-i+1);
        long long currNum=stoll(part);
        if(i==0){
            s=s+part;
            help(num,target,start+1,currNum,currNum);
            s.erase(s.end()-part.size(),s.end());
        }else{
            s=s+'+'+part;
            help(num,target,start+1,currNum,cur+currNum);
            s.erase(s.end()-part.size()-1,s.end());

            s=s+'*'+part;
            help(num,target,start+1,prev*currNum,cur-prev+(prev*currNum));
            s.erase(s.end()-part.size()-1,s.end());

            s=s+'-'+part;
            help(num,target,start+1,-currNum,cur-currNum);
            s.erase(s.end()-part.size()-1,s.end());
        }
    }
   }
    vector<string> addOperators(string num, int target) {
       help(num,target,0,0,0);
       return sa;
    }
};
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