<p>The string <code>&quot;PAYPALISHIRING&quot;</code> is written in a zigzag pattern on a given number of rows like this: (you may want to display this pattern in a fixed font for better legibility)</p>

<pre>
P   A   H   N
A P L S I I G
Y   I   R
</pre>

<p>And then read line by line: <code>&quot;PAHNAPLSIIGYIR&quot;</code></p>

<p>Write the code that will take a string and make this conversion given a number of rows:</p>

<pre>
string convert(string s, int numRows);
</pre>

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

<pre>
<strong>Input:</strong> s = &quot;PAYPALISHIRING&quot;, numRows = 3
<strong>Output:</strong> &quot;PAHNAPLSIIGYIR&quot;
</pre>

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

<pre>
<strong>Input:</strong> s = &quot;PAYPALISHIRING&quot;, numRows = 4
<strong>Output:</strong> &quot;PINALSIGYAHRPI&quot;
<strong>Explanation:</strong>
P     I    N
A   L S  I G
Y A   H R
P     I
</pre>

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

<pre>
<strong>Input:</strong> s = &quot;A&quot;, numRows = 1
<strong>Output:</strong> &quot;A&quot;
</pre>

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

<ul>
	<li><code>1 &lt;= s.length &lt;= 1000</code></li>
	<li><code>s</code> consists of English letters (lower-case and upper-case), <code>&#39;,&#39;</code> and <code>&#39;.&#39;</code>.</li>
	<li><code>1 &lt;= numRows &lt;= 1000</code></li>
</ul>

class Solution {
public:
    string convert(string s, int numRows) {
        int n = s.size();
        vector<vector<char>> mat;
        mat.push_back(vector<char>{});
        for (int i = 0; i < n; i++) {
            if (mat.back().size()==numRows) {              
                int new_col_count = numRows - 2;
                for ( int j = 0; j < new_col_count; ++j ) {
                    vector<char> new_column(numRows, ' ');
                    new_column[numRows-2-j] = s[i];
                    mat.push_back(new_column);
                    i++;
                    if ( i == n) {
                        break;
                    }
                }
                
                if ( i < n) {
                    mat.push_back(vector<char>{});
                }
            }
            mat.back().push_back(s[i]);
        }

        string ret;
        
        for ( int i = 0; i < numRows; ++i ) {
            for ( int j = 0; j < mat.size(); j++ ){
                if ( i < mat[j].size() && mat[j][i]!=' ')
                    ret.push_back(mat[j][i]);
            }
        }

        return ret;

    }
};
33218