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)
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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:
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string convert(string s, int numRows);
Example 1:
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Input: s = "PAYPALISHIRING", numRows = 3
Output: "PAHNAPLSIIGYIR"
Example 2:
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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:
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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;
}