# Zigzag Conversion Problem

## Description

LeetCode Problem 6.

The string “PAYPALISHIRING” 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)

``````1
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P   A   H   N
A P L S I I G
Y   I   R
``````

And then read line by line: “PAHNAPLSIIGYIR”

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

``````1
string convert(string s, int numRows);
``````

Example 1:

``````1
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Input: s = "PAYPALISHIRING", numRows = 3
Output: "PAHNAPLSIIGYIR"
``````

Example 2:

``````1
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Input: s = "PAYPALISHIRING", numRows = 4
Output: "PINALSIGYAHRPI"
Explanation:
P     I    N
A   L S  I G
Y A   H R
P     I
``````

Example 3:

``````1
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Input: s = "A", numRows = 1
Output: "A"
``````

Constraints:

• 1 <= s.length <= 1000
• s consists of English letters (lower-case and upper-case), ‘,’ and ‘.’.
• 1 <= numRows <= 1000

## Sample C++ Code

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string convert(string s, int nRows) {

if (nRows <= 1)
return s;

const int len = (int)s.length();
string *str = new string[nRows];

int row = 0, step = 1;
for (int i = 0; i < len; ++i)
{
str[row].push_back(s[i]);

if (row == 0)
step = 1;
else if (row == nRows - 1)
step = -1;

row += step;
}

s.clear();
for (int j = 0; j < nRows; ++j)
{
s.append(str[j]);
}

delete[] str;
return s;
}
``````