6. 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

And then read line by line: "PAHNAPLSIIGYIR"

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".

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class Solution {
public:
    string convert(string s, int numRows) {
        if(numRows==1) return s;
        int length=s.length();
        char table[numRows][length*length/numRows*2+1];
        for(int r=0;r<numRows;r++)
        {
            for(int c=0;c<length*length/numRows*2+1;c++)
            {
                table[r][c]=' ';
            }
        }
        bool tag=0;
        int r=-1,c=0,i=0;
        while(1)
        {
            if((r==0||tag==0)&&r<numRows-1)
            {
                tag=0;
                r++;
                //cout<<"r="<<r<<",c="<<c<<",code="<<s[i];
                table[r][c]=s[i];
                i++;
                //cout<<",i="<<i<<endl;
            }
            if(i>=s.length()) break;
            if((r==numRows-1||tag==1)&&r>0)
            {
                tag=1;
                c++;
                r--;
                //cout<<"r="<<r<<",c="<<c<<",code="<<s[i];
                table[r][c]=s[i];
                i++;
                //cout<<",i="<<i<<endl;
            }
            if(i>=s.length()) break;
        }
        string ans;
        for(int r=0;r<numRows;r++)
        {
            for(int c=0;c<length*length/numRows*2+1;c++)
            {
                if(table[r][c]!=' ')
                {
                    ans+=table[r][c];
                }
            }
        }
        return ans;
    }
};