<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) {
        if (numRows == 1) {
            return s;
        }

        std::vector<std::vector<char>> rows;
        rows.resize(numRows);

        int curr_row = 0;
        int curr_col = 0;
        std::string curr_dir = "down";
        

        for (char c : s) {
            rows.at(curr_row).push_back(c);
            if (curr_dir == ("down") && curr_row < numRows - 1) {
                curr_row ++;
            } else if (curr_dir == ("down") && curr_row == numRows - 1) {
                curr_row -= 1;
                curr_col ++;
                curr_dir = "up";
            } else if (curr_dir == ("up") && curr_row > 0) {
                curr_row --;
                curr_col ++;
            } else if (curr_dir == ("up") && curr_row == 0) {
                curr_row ++;
                curr_dir = "down";
            }
        }

        for (std::vector<char> r : rows) {
            r.resize(curr_col);
        }

        std::string final_str;
        
        for (std::vector<char> r : rows) {
            for (char s : r) {
                final_str += s;
            }
        }
        return final_str;
    }
};
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