題目：

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)

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 s, int numRows);

Example 1:

Input: s = “PAYPALISHIRING”, numRows = 3
Output: “PAHNAPLSIIGYIR”

Example 2:

理解：

把給定的字串按zigzag的形式寫出來，然後按行輸出。下面是我的實現。

實現：

class Solution {
public:
	string convert(string s, int numRows) {
        if(numRows==1) return s;
        string res;		
		for (int i = 0; i < numRows; ++i) {
			for (int j = i;;) {
				if (i != numRows - 1) {
					res += s[j];
					j += 2 * numRows - 2 - 2 * i;
					if (j >= s.size())
						break;
				}
				if (i != 0) {
					res += s[j]; 
					j += 2 * i;	
					if (j >= s.size())
						break;
				}
			}
		}
		return res;
	}
};