[6] N 字形变换

 1 /**
 2  * @param {string} s
 3  * @param {number} numRows
 4  * @return {string}
 5  */
 6 var convert = function (s, numRows) {
 7   if (numRows === 1) {
 8     return s;
 9   }
10 
11   let ans = "";
12   const n = s.length;
13   const r = numRows;
14   const t = r * 2 - 2;
15 
16   for (let i = 0; i < r; i++) {
17     for (let j = 0; j + i < n; j += t) {
18       ans += s[j + i];
19       if (i > 0 && i < r - 1 && j + t - i < n) {
20         ans += s[j + t - i];
21       }
22     }
23   }
24 
25   return ans;
26 };