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" .

[java]  view plain  copy

1. public class Solution {  
2.     public String convert(String s, int numRows) {  
3.         if(numRows==1) return s;  
4.         StringBuilder sb = new StringBuilder();  
5.         for(int i=0;i<numRows;i++){  
6.             int j = i;  
7.             boolean flag = true;  
8.             while(j<s.length()){  
9.                 sb.append(s.charAt(j));  
10.                 if(i==0||i==numRows-1){  
11.                     j += 2*(numRows-1);  
12.                 }else{  
13.                     if(flag){  
14.                         j += 2*(numRows-1-i);                         
15.                     }else{  
16.                         j += 2*i;  
17.                     }  
18.                     flag = !flag;  
19.                 }  
20.             }  
21.         }  
22.         return sb.toString();  
23.     }  
24. }  

原文链接http://blog.youkuaiyun.com/crazy__chen/article/details/45456781