spiralMatrix.js

/**
 * 回形矩阵
 * @param  {Number} n - 矩阵尺寸
 * @return {String}
 */
function spiralMatrix (n) {
  let matrix = [];
  let a = n ** 2;
  let p = a.toString().length;
  for (let x = 0; x < n; x++) {
    for (let y = 0; y < n; y++) {
      let cx = n - 1 - x;
      let cy = n - 1 - y;
      let z = Math.min(x, y, cx, cy);
      let m = n - z * 2;
      let b = a - m ** 2;
      let cb = b + (m - 1) * 2;
      let v = x <= y ? (x - z) + (y - z) + b
                     : (cx - z) + (cy - z) + cb;
      matrix.push(v.toString().padStart(p, " "));
    }
    matrix.push("\n");
  }
  return matrix.join(" ").replace(/\n\s/g, "\n");
}

test.js

console.log(spiralMatrix(6));