leetcode - ZigZag Conversion

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

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".

class Solution {
public:
    std::string convert(std::string s, int nRows) {
		if(nRows==1)
        {
            return s;
        }
        std::string result;
        int t = nRows*2-2;
        for(int i = 0;i<=t/2;++i)
        {
            for(int j = 0;j