[Leetcode]#6 ZigZag Conversion

//#6 ZigZag Conversion
//108ms 4.86%
class Solution {
public:
string convert(string s, int numRows)
{
vector < vector<char> > v_v;
while(!s.empty())
{
vector<char> v(numRows, '0');
for(int i=0; i<numRows; i++)
{
if(!s.empty())
{
v[i] = s[0];
s.erase(s.begin());
}
}
v_v.push_back(v);
for(int i=0; i<numRows-2; i++)
{
if(!s.empty())
{
vector<char> v(numRows, '0');
v[numRows-i-2] = s[0];
s.erase(s.begin());
v_v.push_back(v);
}
}
}
string result;
for(int i=0; i<numRows; i++)
{
for(unsigned int j=0; j<v_v.size(); j++)
{
if(v_v[j][i] != '0')
{
result.push_back(v_v[j][i]);
}
}
}
return result;
}
};