Zigzag Conversion | Leetcode solution

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 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;
    }
};





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