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".

分两次循环，第一次是列，第二次是斜线。

java需使用stringbuffer才不会超时，使用string超时了。

 1 public class Solution {
 2     public String convert(String s, int nRows) {
 3         if (nRows==1) {
 4             return s;
 5         }
 6
 7         StringBuffer[]    reBuffers=new StringBuffer[nRows];
 8         for (int i = 0; i < reBuffers.length; i++) {
 9             reBuffers[i]=new StringBuffer();
10         }
11         int i=0,j=0,C=nRows-2;
12         while (i<s.length()) {
13             for (j = 0; j<nRows&&i<s.length() ;j++) {
14
15                 reBuffers[j].append(s.charAt(i++));
16
17             }
18
19             for (j = C; i<s.length()&&j>0;j--) {
20
21                 reBuffers[j].append(s.charAt(i++));
22
23             }
24
25         }
26
27         StringBuffer    res=new StringBuffer();
28         for (int k = 0; k < nRows; k++) {
29             res.append(reBuffers[k]);
30         }
31         return res.toString();
32     }
33 }