为什么reduce()在乘以大数组时返回NaN

Question

我正在解决 leetcode 的问题 1822，但我坚持使用返回 NaN 的 reduce() 。

有一个函数 signFunc(x) 返回：

如果 x 为正，则为 1。如果 x 为负数，则为 -1。如果 x 等于 0，则为 0。您将获得一个整数数组 nums。令 Product 为数组 nums 中所有值的乘积。

返回signFunc(产品)。

我尝试的解决方案：

var arraySign = function(nums) {return Math.sign(nums.reduce((acc, curr) => acc * curr));};

console.log(arraySign([1,5,0,2,-3]));

当我传递像 [1,5,0,2,-3] 这样的简单数组时，一切都很好，但是当我传递像这样的怪物时

[1,28,-91,-62,-36,-1,-84,-90,-92,61,6,-58,-60,2,51,-15,-18,-81,87 ,84,100,-84,-13,-87,-33,72,-72,-59,-79,28,-69,-97,-93,17,67,11,-12,19,5, 42,-85,71,-77,-82,26,-58,-51,-14,63,-85,-86,66,47,57,-86,-25,-75,59,- 17,-71,89,-78,-42,30,39,61,-96,-30,-29,-92,-90,69,20,65,32,92,44,-71,- 18,87,-86,23,-96,-21,-49,-96,-98,35,-11,-1,81,-48,68,5,75,57,-30,-7 ,32,86,-29,-86,-61,45,-31,-93,-26,-9,86,57,-52,75,68,-58,14,27,-94,47 ,-38,-44,75,-83,21,-83,43,62,74,97,78,43,54,28,64,-19,-89,88,68,18,-96, -83,-25,-71,88,-84,-24,-61,72,-90,-56,29,46,56,51,16,66,-2,65,-95,16, 51,42,61,99,89,-93,59,-99,69,26,-61,21,41,40,-4,-49,3,-96,57,65,72,-41 ,-77,-4,61,71,-88,21,-95,38,64,92,0,-63]

var arraySign = function(nums) {return Math.sign(nums.reduce((acc, curr) => acc * curr));};

console.log(arraySign([1,28,-91,-62,-36,-1,-84,-90,-92,61,6,-58,-60,2,51,-15,-18,-81,87,84,100,-84,-13,-87,-33,72,-72,-59,-79,28,-69,-97,-93,17,67,11,-12,19,5,42,-85,71,-77,-82,26,-58,-51,-14,63,-85,-86,66,47,57,-86,-25,-75,59,-17,-71,89,-78,-42,30,39,61,-96,-30,-29,-92,-90,69,20,65,32,92,44,-71,-18,87,-86,23,-96,-21,-49,-96,-98,35,-11,-1,81,-48,68,5,75,57,-30,-7,32,86,-29,-86,-61,45,-31,-93,-26,-9,86,57,-52,75,68,-58,14,27,-94,47,-38,-44,75,-83,21,-83,43,62,74,97,78,43,54,28,64,-19,-89,88,68,18,-96,-83,-25,-71,88,-84,-24,-61,72,-90,-56,29,46,56,51,16,66,-2,65,-95,16,51,42,61,99,89,-93,59,-99,69,26,-61,21,41,40,-4,-49,3,-96,57,65,72,-41,-77,-4,61,71,-88,21,-95,38,64,92,0,-63]));

我只得到“NaN”返回。此时我通过 if 跳过了这个错误：

var arraySign = function(nums) {
let product = nums.reduce((acc, curr) => acc * curr);

if(product>0) return 1;
else if (product<0) return -1;
else return 0;};

但我想知道：为什么减少在这个问题上不起作用？reduce() 有限制吗？

Answer 1

问题不在于reduce. 问题是你要乘以很多数字，相当于Infinity(或-Infinity)，然后你还要将其乘以0。但Infinity * 0给出NaN.

您只需将数字的符号相乘即可解决此问题：

function arraySign(nums) {
  return nums.reduce((acc, curr) => acc * Math.sign(curr), 1);
};