计算实际时间天数（时间范围去重）

Question

举例 1.2-1.5 ， 1.4-1.6
去重后就是 1.2 1.3 1.4 1.5 .16 一共5天

Answer 1

function getDays (ranges: readonly (readonly [number, number])[]): number {
  const days = new Set<number>();
  for (const [start, end] of ranges) {
    for (let time = start; end >= time; time += 8.64e7) {
      days.add(time);
    }
  }
  return days.size;
}

getDays([
  [Date.parse("2021-01-02"), Date.parse("2021-01-05")],
  [Date.parse("2021-01-04"), Date.parse("2021-01-06")],
]);