Leetcode 第6题

string convert(string s, int numRows) {
        if(numRows==1)return s;
	vector<string> res(numRows, "");
	for (int i = 0; i<s.size(); i++)
	{
		int p = i % (2 * (numRows - 1)), q = 2 * (numRows - 1);
		if (p<numRows - 1)
			res[p] += s[i];
		else if (p<q)
			res[q - p] += s[i];
	}
	string ans;
	for (int i = 0; i<numRows; i++)
		ans += res[i];
	return ans;
}