6.z-字形变换.ts

/*
 * @lc app=leetcode.cn id=6 lang=typescript
 *
 * [6] Z 字形变换
 */

// @lc code=start
function convert(s: string, numRows: number): string {
  if (numRows === 1 || numRows >= s.length) return s;

  const t = numRows * 2 - 2;
  const ans: string[] = [];
  for (let i = 0; i < numRows; i++) {
    for (let j = 0; j < s.length - i; j += t) {
      ans.push(s[j + i]);
      if (0 < i && i < numRows - 1 && j + t - i < s.length) {
        ans.push(s[j + t - i]);
      }
    }
  }
  return ans.join("");
}
// @lc code=end