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   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".

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<len)        {           for (int idx = 0; idx < nRows && i < len; idx++) // vertically down            st[idx] += (s[i++]);        for (int idx = nRows-2; idx >= 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];    }};