[Leetcode] ZigZag Conversion

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:

http://harrifeng.github.io/algo/leetcode/zigzag-conversion.html

public class Solution {
    public String convert(String s, int nRows) {
        if(nRows==1)
            return s;
        int zigSize=2*nRows-2;
        StringBuilder[] sb=new StringBuilder[nRows];
        for(int i=0;i<nRows;++i){
            sb[i]=new StringBuilder();
        }
        for(int i=0;i<s.length();++i){
            int newi=i%zigSize;
            if(newi<nRows){
                sb[newi].append(s.charAt(i));
            }else{
                sb[zigSize-newi].append(s.charAt(i));
            }
        }
        StringBuilder result=new StringBuilder();
        for(StringBuilder i:sb){
            result.append(i);
        }
        return result.toString();
    }
}