<p>You are given an integer <code>num</code>. You can swap two digits at most once to get the maximum valued number.</p>

<p>Return <em>the maximum valued number you can get</em>.</p>

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

<pre>
<strong>Input:</strong> num = 2736
<strong>Output:</strong> 7236
<strong>Explanation:</strong> Swap the number 2 and the number 7.
</pre>

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

<pre>
<strong>Input:</strong> num = 9973
<strong>Output:</strong> 9973
<strong>Explanation:</strong> No swap.
</pre>

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

<ul>
	<li><code>0 &lt;= num &lt;= 10<sup>8</sup></code></li>
</ul>

class Solution {
public:
    int maximumSwap(int num) {
        vector<int> d, mx;
        int i = 0;
        while (num) {
            d.push_back(num%10);
            if (mx.empty() or d[mx.back()] < num%10)
                mx.push_back(i);
            else 
                mx.push_back(mx.back());
            num /= 10;
            i++;
        }
        for (int i = d.size()-1; i >= 0; i--) {
            if (d[i] != d[mx[i]]) {
                swap(d[i], d[mx[i]]);
                break;
            }
        }
        int res = 0;
        for (int i = d.size()-1; i >= 0; i--) {
            res = res * 10 + d[i];
        }
        return res;
    }
};
    // 7766
7500