Math Issues

Oh no, our Math object was "accidently" reset. Can you re-implement some of those functions? We can assure, that only non-negative numbers are passed as arguments. So you don't have to consider things like undefined, null, NaN, negative numbers, strings and so on.

Here is a list of functions, we need:

• Math.round()
• Math.ceil()
• Math.floor()

题目意思是js 的内置对象Math 不能用了，让我们来修复Math.round()这些方法。

只要能想到parseInt()这个方法，这个问题就很简单了。我的常规解法：

Math.round = function(number) {
  return (number - parseInt(number) >= 0.5) ? parseInt(number) + 1 : parseInt(number) ;
};

Math.ceil = function(number) {
  return (parseInt(number) === number) ? number : parseInt(number) + 1;
};

Math.floor = function(number) {
  return parseInt(number);
};

　某神的解法：

Math.round = function(number) {
  return Math.floor(number + 0.5);
};

Math.ceil = function(number) {
  return (number | 0) + (number % 1 !== 0 ? 1 : 0);
};

Math.floor = function(number) {
  return number | 0;
};

看了某神的解法，瞬间感觉自己长了个假脑子，不说了，我去哭一会儿，把脑子里的水倒一倒。