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".
思路：找出规律，然后按照新字符串的顺序放到新字符串中，注意下标。
class Solution { public String convert(String s, int numRows) { if(numRows<=1||numRows>=s.length())return s; StringBuffer newString=new StringBuffer(); int gap=2*numRows-2;//周期数 int n=numRows;//循环数 int index; while(n-->0){ if(n==numRows-1||n==0){ for(int i=numRows-n-1;i<s.length();i=i+gap){ newString.append(s.charAt(i)); } } else{ for(int i=numRows-n-1;i<s.length();i=i+gap){ newString.append(s.charAt(i)); if((index=(i/gap*gap+2*numRows-(i%gap)-2))<s.length()) newString.append(s.charAt(index)); } } } return newString.toString(); } }