Pattern-22 The-Number-Pattern.js

function theNumberPattern(num) {
  // Outer loop for no. of rows
  for (let i = 0; i < 2 * num - 1; i++) {
    // inner loop for no. of columns.
    for (let j = 0; j < 2 * num - 1; j++) {
      // Initialising the top, down, left and right indices of a cell.
      let top = i;
      let bottom = j;
      let right = 2 * num - 2 - j;
      let left = 2 * num - 2 - i;

      // Min of 4 directions and then we subtract from num
      // because previously we would get a pattern whose border
      // has 0's, but we want with border N's and then decrease inside.
      process.stdout.write(
        num - Math.min(Math.min(top, bottom), Math.min(left, right)) + " "
      );
    }

    // As soon as the numbers for each iteration are printed, we move to the
    // next row and give a line break otherwise all numbers
    // would get printed in 1 line.
    console.log();
  }
}

theNumberPattern(5);
// OUTPUT
// 5 5 5 5 5 5 5 5 5
// 5 4 4 4 4 4 4 4 5
// 5 4 3 3 3 3 3 4 5
// 5 4 3 2 2 2 3 4 5
// 5 4 3 2 1 2 3 4 5
// 5 4 3 2 2 2 3 4 5
// 5 4 3 3 3 3 3 4 5
// 5 4 4 4 4 4 4 4 5
// 5 5 5 5 5 5 5 5 5