6: ZigZag Conversion (Medium)

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

/**
* @param {string} s
* @param {number} numRows
* @return {string}
*/
var convert = function (inputString, targetRows) {
   if (targetRows == 1) {
       return inputString;
   }

   // Start the process on row 1, heading down
   let currentRow = 1;
   let headingDown = true;

   // Initialise an array to store the zigzag data
   let zigZagArray = [];

   // Loop through the requested number of rows
   for (let i = 0; i < targetRows; i++) {
       // Initialise each zigzag row as an empty array
       zigZagArray[i] = [];
   }

   // Loop through the string
   for (let i = 0; i < inputString.length; i++) {
       // Add the current letter to the current row
       zigZagArray[currentRow - 1].push(inputString[i]);

       if (headingDown) {
           currentRow++;

           // Check if we've exceeded the maximum number of rows
           if (currentRow > targetRows) {
               // Start heading back up again
               currentRow = targetRows - 1;
               headingDown = false;
           }
       } else {
           currentRow--;

           // Check if we've exceeded the top row
           if (currentRow < 1) {
               // Start heading down again
               currentRow = 2;
               headingDown = true;
           }
       }
   }

   // Initialise a return string
   let totalString = '';

   // Loop through the constructed rows
   for (let i = 0; i < targetRows; i++) {
       // Append the row's characters joined together
       totalString += zigZagArray[i].join('');
   }

   return totalString;
};

  None