6. ZigZag Conversion

https://leetcode.com/problems/zigzag-conversion/

Visit by row:

//12 ms    8 MB
class Solution {
public:
    string convert(string s, int numRows) {
        if(numRows == 1)
            return s;
        string result = "";
        int str_len = s.length(); //total length
        int cyc_len = 2*numRows - 2; //corner length
        for (int i = 0; i < numRows; i++){
            for (int j = 0; i + j < str_len; j += cyc_len){
                result += s[i + j];
                if(i != 0 && i != numRows - 1 && j + cyc_len - i < str_len)
                    result += s[j + cyc_len - i];
            }
        }
        return result;
    }
};

• Time Complexity: O(n)
• Space Complexity: O(n)