leetcode zigzag

题目要求：

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".

代码贴出！已AC。

class Solution {
public:
    string convert(string s, int nRows) {
        if (nRows <= 1 || s.length() == 0)  
           return s;  
  
        int len = s.size();
        string st[nRows];
        int i = 0;
        while(i= 1 && i < len; idx--) // obliquely up
	            st[idx] += (s[i++]);
        }
        for (int idx = 1; idx < nRows; idx++)
	        st[0].append(st[idx]);
	    return st[0];
    }
};