class Solution {
public:
string convert(string s, int numRows) {
if(numRows==1)
return s;
else
{
int len=s.size();
int count=0;
int interval=(numRows<<1)-2;
string res(len,' ');
for(int j=0;j<len;j=j+interval)
res[count++]=s[j];
for(int k=1;k<numRows-1;k++)
{
int inter=k<<1;
for(int j=k;j<len;j+=inter)
{
res[count++]=s[j];
inter=interval-inter;
}
}
for(int j=numRows-1;j<len;j=j+interval)
res[count++]=s[j];
return res;
}
}
};