6. ZigZag Conversion

#include<iostream>
#include<string>
using namespace std;
string convert(string s, int numRows) {
	  if(s == "" || s.length() == 0)	return "";
	  if(numRows == 1)	return s;
	  string res = "";
	  int size = numRows * 2 - 2;
	  for(int i = 0; i < numRows; ++i){
	  	for(int j = i; j < s.length(); j += size){
	  		res = res + s[j];
	  		if(i != 0 && i != numRows - 1 && j + size - 2 * i < s.length())
	  			res = res + s[j + size - 2 * i];
		  }
	  }
	  return res;
}
int main(){
	string s;
	int n;
	cin >> s >>  n;
	cout << convert(s, n);
	return 0;
}