3、生兔子

有一对兔子，从出生后第三个月起每个月都生一对兔子，小兔子长到三个月后每个月又生一对兔子，假如兔子都不死，问一年中每个月各有多少对兔子？

let [rabbits, months] = [[0], [...new Array(12)]];

const result = months.reduce(counts => {

  rabbits = rabbits.reduce((origin, item) => {
    origin.push(++item);
    return origin;
  }, []);

  rabbits.forEach(rabbit => rabbit >= 3 && rabbits.push(1));

  counts.push(rabbits.length);

  return counts;

}, []);

console.log(result); // [ 1, 1, 2, 3, 5, 8, 13, 21, 34, 55, 89, 144 ]

以上为代码演示，欢迎指正！