Question
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)
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:
string convert(string text, int nRows);
convert("PAYPALISHIRING", 3)should return"PAHNAPLSIIGYIR".
Solution
#include <string>
using namespace std;
class Solution {
public:
string convert(string s, int numRows) {
if (numRows == 1) {
return s;
}
const int size = s.length();
string result;
for (int row = 0; row < numRows; row++) {
const int delta1 = 2 * (numRows - row - 1);
const int delta2 = 2 * (numRows - 1);
int step = 0;
int pos = row;
while (pos < size) {
result.push_back(s[pos]);
step++;
if (row == 0) {
pos += delta1;
} else if (row == numRows - 1) {
pos += delta2;
} else {
if (step % 2 == 1) {
pos += delta1;
} else {
pos += 2 * row;
}
}
}
}
return result;
}
};