Zigzag Conversion | Leetcode solution

 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 s, int numRows);

 

Example 1:

Input: s = "PAYPALISHIRING", numRows = 3
Output: "PAHNAPLSIIGYIR"

Example 2:

Input: s = "PAYPALISHIRING", numRows = 4
Output: "PINALSIGYAHRPI"
Explanation:
P     I    N
A   L S  I G
Y A   H R
P     I

Example 3:

Input: s = "A", numRows = 1
Output: "A"

 

Constraints:

• 1 <= s.length <= 1000
• s consists of English letters (lower-case and upper-case), ',' and '.'.
• 1 <= numRows <= 1000

solution:

class Solution {

public:

    string convert(string s, int numRows) {

        vector<string> v(numRows, "");

        int i =0;

        int n = s.length();

        while(i<n){

            

            for(int j =0; j<numRows && i<n; j++ ){

                v[j].push_back(s[i++]);

            }

            

            for(int j =numRows-2; j>=1 && i<n; j--){

                v[j].push_back(s[i++]);

            }

        }

        

        string res ="";

        for(auto i : v){

            res+=i;

        }

        return res;

    }

};

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