[leetcode] ZigZag Conversion *

/*
 * Just find the rule; Do not forget to check
 * special cases (e.g. nRows = 1 ...)
 *
 * @author: HZT
 * @date: 2013-3-9
 */

#include <iostream>
#include <string>
using namespace std;

class Solution {
public:
    string convert(string s, int nRows) {
        // Start typing your C/C++ solution below
        // DO NOT write int main() function

        // DO NOT forget this!!
        if(nRows == 1) return s;
        if(s.empty()) return s;
        int len = s.length();

        char* ans = new char[len+1];

        int idx, ansIdx=0;
        int delta = 2 * nRows - 2;
        // each row
        for(int r=1; r<=nRows; r++){
            idx = r;
            while(idx <= len){
                ans[ansIdx++] = s[idx-1];
                if(r!=1 && r!=nRows && 2*nRows-2*r+idx <= len){
                    ans[ansIdx++] = s[2*nRows-2*r+idx-1];
                }

                idx += delta;
            }
        }

        ans[len] = '\0';
        return ans;
    }
};

int main(){
    string s = "PAYPALISHIRING";
    int nRows = 3;

    //string s = "A";
    //int nRows = 1;

    cout << (new Solution)->convert(s, 3) << endl;

    return 0;

}