ZigZag Conversion

题目描述如下

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   NA P L S I I GY   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".

采用方案：

public String convert(String s, int nRows) {    char[] c = s.toCharArray();    int len = c.length;    StringBuffer[] sb = new StringBuffer[nRows];    for (int i = 0; i < sb.length; i++) sb[i] = new StringBuffer();        int i = 0;    while (i < len) {        for (int idx = 0; idx < nRows && i < len; idx++) // vertically down            sb[idx].append(c[i++]);        for (int idx = nRows-2; idx >= 1 && i < len; idx--) // obliquely up            sb[idx].append(c[i++]);    }    for (int idx = 1; idx < sb.length; idx++)        sb[0].append(sb[idx]);    return sb[0].toString();}