<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 size = s.size();
        
        if (numRows == 1 || numRows >= size) {
            return s; 
        }

        int pairCol = numRows - 1;
        int charInPair = numRows + (pairCol - 1);
        int maxpair = size / charInPair;
        int checkmaxpair = size % charInPair == 0 ? 0 : 1;

        int completeCol = maxpair * pairCol;
        int remainingChar = size % charInPair;

        int remainingCol = 0;
        if (remainingChar > numRows) {
            remainingCol = remainingChar - numRows;
        }
        if (checkmaxpair == 1) {
            remainingCol++;
        }
        completeCol += remainingCol;

        vector<vector<char>> ans(numRows, vector<char>(completeCol, ' '));
        
        int count = 0;
        int j = 0;

        
        for (int i = 0; i < completeCol && count < size; i++) {
            if (i % pairCol == 0) {
                // Vertical column
                for (j = 0; j < numRows && count < size; j++) {
                    ans[j][i] = s[count++];
                }
                j = numRows - 2; 
            } else {
               
                ans[j][i] = s[count++];
                j--; 
            }
        }

        
        string answer;
        for (int j = 0; j < numRows; j++) {
            for (int k = 0; k < completeCol; k++) {
                if (ans[j][k] != ' ') {
                    answer += ans[j][k];
                }
            }
        }
        
        return answer;
    }
};
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