<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>

#include <string>
#include <vector>
using namespace std;

class Solution {
public:
    vector<string> addOperators(string num, int target) {
        vector<string> result;
        helper(result, "", num, target, 0, 0, 0);
        return result;
    }

private:
    void helper(vector<string>& result, string path, string num, int target, int pos, long currVal, long prevVal) {
        if (pos == num.size()) {
            if (currVal == target) {
                result.push_back(path);
            }
            return;
        }

        for (int i = pos; i < num.size(); i++) {
            if (i != pos && num[pos] == '0') break;  // Prevent numbers with leading zeros

            string part = num.substr(pos, i - pos + 1);
            long current = stol(part);

            if (pos == 0) {
                // First number in the expression
                helper(result, path + part, num, target, i + 1, current, current);
            } else {
                // Addition
                helper(result, path + "+" + part, num, target, i + 1, currVal + current, current);
                // Subtraction
                helper(result, path + "-" + part, num, target, i + 1, currVal - current, -current);
                // Multiplication
                helper(result, path + "*" + part, num, target, i + 1, currVal - prevVal + prevVal * current, prevVal * current);
            }
        }
    }
};

52471