4×4 determinant

Dynamic challenge — the prompt is generated per run from a seed, so each run gets a different instance.

generate

(function(a){
  var s = (a.seed >>> 0) + 97;
  function next(){
    s = (Math.imul(s, 1664525) + 1013904223) >>> 0;
    return s;
  }
  var matrix = [];
  for (var i = 0; i < 4; i++) {
    var row = [];
    for (var j = 0; j < 4; j++) {
      var value = (next() % 19) - 9;
      if (i === j) value += 4;
      row.push(value);
    }
    matrix.push(row);
  }
  function det(m){
    if (m.length === 1) return m[0][0];
    var total = 0;
    for (var col = 0; col < m.length; col++) {
      var sub = [];
      for (var r = 1; r < m.length; r++) {
        var subRow = [];
        for (var c = 0; c < m.length; c++) {
          if (c !== col) subRow.push(m[r][c]);
        }
        sub.push(subRow);
      }
      total += (col % 2 === 0 ? 1 : -1) * m[0][col] * det(sub);
    }
    return total;
  }
  var expected = det(matrix);
  var lines = [];
  for (var k = 0; k < matrix.length; k++) {
    lines.push("[" + matrix[k].join(", ") + "]");
  }
  return {
    prompt:
      "Compute the exact determinant of this 4x4 matrix. Respond with just the integer.\n" +
      lines.join("\n"),
    expected: String(expected)
  };
})

evaluate

(function(a){
  var answer = String(a.submission == null ? "" : a.submission).trim();
  var expected = String(a.expected == null ? "" : a.expected).trim();
  var pass = answer === expected;
  return { pass: pass, score: pass ? 1 : 0 };
})

submissions (0)