<p>You are given a string of digits <code>num</code>, such as <code>&quot;123456579&quot;</code>. We can split it into a Fibonacci-like sequence <code>[123, 456, 579]</code>.</p>

<p>Formally, a <strong>Fibonacci-like</strong> sequence is a list <code>f</code> of non-negative integers such that:</p>

<ul>
	<li><code>0 &lt;= f[i] &lt; 2<sup>31</sup></code>, (that is, each integer fits in a <strong>32-bit</strong> signed integer type),</li>
	<li><code>f.length &gt;= 3</code>, and</li>
	<li><code>f[i] + f[i + 1] == f[i + 2]</code> for all <code>0 &lt;= i &lt; f.length - 2</code>.</li>
</ul>

<p>Note that when splitting the string into pieces, each piece must not have extra leading zeroes, except if the piece is the number <code>0</code> itself.</p>

<p>Return any Fibonacci-like sequence split from <code>num</code>, or return <code>[]</code> if it cannot be done.</p>

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

<pre>
<strong>Input:</strong> num = &quot;1101111&quot;
<strong>Output:</strong> [11,0,11,11]
<strong>Explanation:</strong> The output [110, 1, 111] would also be accepted.
</pre>

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

<pre>
<strong>Input:</strong> num = &quot;112358130&quot;
<strong>Output:</strong> []
<strong>Explanation:</strong> The task is impossible.
</pre>

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

<pre>
<strong>Input:</strong> num = &quot;0123&quot;
<strong>Output:</strong> []
<strong>Explanation:</strong> Leading zeroes are not allowed, so &quot;01&quot;, &quot;2&quot;, &quot;3&quot; is not valid.
</pre>

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

<ul>
	<li><code>1 &lt;= num.length &lt;= 200</code></li>
	<li><code>num</code> contains only digits.</li>
</ul>

class Solution {
public:
    vector<int> splitIntoFibonacci(string num) {
        vector<int> result;
        int n = num.size();

        for (int firstEnd = 1; firstEnd <= n / 2; firstEnd++) {
            // Leading zeros check
            if (num[0] == '0' && firstEnd > 1)
                break;
            long long first = stoll(num.substr(0, firstEnd));
            if (first > INT_MAX)
                break;

            for (int secondEnd = firstEnd + 1; secondEnd < n; secondEnd++) {
                // Leading zeros check
                if (num[firstEnd] == '0' && secondEnd > firstEnd + 1)
                    break;
                long long second =
                    stoll(num.substr(firstEnd, secondEnd - firstEnd));
                if (second > INT_MAX)
                    break;

                result.clear();
                result.push_back(first);
                result.push_back(second);

                if (checkSequence(num, secondEnd, first, second, result)) {
                    return result;
                }
            }
        }

        return {};
    }

private:
    bool checkSequence(const string& num, int index, long long first,
                       long long second, vector<int>& result) {

        long long next = first + second;

        // Check if the result is out of int range
        if (next > INT_MAX)
            return false;

        string nextStr = to_string(next);

        // If the next number in the sequence does not match the substring at
        // the current index, break
        if (num.substr(index, nextStr.size()) != nextStr) {
            return false;
        }

        // Move the index forward and update the sequence
        index += nextStr.size();
        result.push_back(next);

        // If we reach the end of the string, return true
        if (index == num.size()) {
            return true;
        }

        return checkSequence(num, index, second, next, result);
    }
};

10900