[Leetcode] 6. Zigzag Conversion Typescript

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

 

 

문자열이 특정 사이클((numRows - 1) * 2) 주기로 반복됨

 

function convert(s: string, numRows: number): string {
  if (s.length < numRows || s.length < 2 || numRows < 2) {
    return s;
  }

  const result = new Array(numRows).fill('');
  const cycle = (numRows - 1) * 2;

  s.split('').forEach((value, index) => {
    const rest = index % cycle;

    const arrayIndex = rest < numRows ? rest : cycle - rest;
    result[arrayIndex] += value;
  });

  return result.join('');
}