leetcode#6-ZigZag Conversion-java

题目：

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".

解法一：

public String convert(String s, int numRows) {
   StringBuilder [] sb = new StringBuilder[numRows];
   int length = s.length();
   for(int i=0;inew StringBuilder();
   }
   char[] arr = s.toCharArray();
   int i = 0;
   while(ifor(int dex = 0;dexfor(int dex = numRows-2;dex>=1 && ifor(int j=1;j0].append(sb[j]);
   }
   return sb[0].toString();
}

解法二：

 public String convert(String s, int numRows) {
    StringBuilder [] sb = new StringBuilder[numRows];
    int length = s.length();
    for(int i=0;inew StringBuilder();
    }
    char[] arr = s.toCharArray();
    int incre = 1;
    int index = 0;
    for(int i=0;iindex].append(arr[i]);
        if(index==0){
            incre=1;
        }
        if(index==numRows-1){
            incre = -1;
        }
        index+=incre;
    }
    for(int i=1;i0].append(sb[i]);
    }
    return sb[0].toString();
}