UniLecs - Задача 143

task143.js

function makePyramid(height) {
  if (typeof height !== 'number' && height < 1) throw 'Wrong number';
  // Total number in pyramid is qual height^2
  const total = Math.pow(height, 2);

  // make 2d array filled 0
  // each internal array length qual number of block in this pyramid leyer
  let output = Array.from(
    { length: height},
    (_, i) => Array.from({ length: 2*(i+1) - 1}).fill(0)
  );

  // accepting:
  // array - link to array slice that need to fill
  // start - start number
  // iteration - number of recutsion iteration
  function fill(array, start, iteration) {
    if (!array.length) return;

    // step 1: fill horizontal leyer -
    // last array in slice
    let h_array = array[array.length-1];
    let size = h_array.length - iteration;
    for (let i = iteration; i < size; i++) {
      h_array[i] = start;
      start ++;
      if (start > total) return;
    }

    // step 2: fill right side
    for (let i = array.length - 2; i > 0; i--) {
      array[i][array[i].length - 1 - iteration] = start;
      start ++;
      if (start > total) return;
    }

    // step 3: fill left side
    for(let i = 0; i < array.length - 1; i++) {
      array[i][iteration] = start;
      start ++;
      if (start > total) return;
    }

    fill(array.slice(1, array.length - 1), start, iteration + 1)
  }

  fill(output, 1, 0);

  return output;
}

// print pyramid layers
function printOut(array, print) {
  const str = array.reduce((str, arr) => {
    return str + arr.join(' ') + '\n';
  }, '')
  print(str)
}

printOut(makePyramid(4), console.log);