每日两题 T30

输入：nums = [1,1,2,1,1], k = 3
输出：2
解释：包含 3 个奇数的子数组是 [1,1,2,1] 和 [1,2,1,1] 。

输入：nums = [2,4,6], k = 1
输出：0
解释：数列中不包含任何奇数，所以不存在优美子数组。

输入：nums = [2,2,2,1,2,2,1,2,2,2], k = 2
输出：16

/**
 * @param {number[]} nums
 * @param {number} k
 * @return {number}
 */
const numberOfSubarrays = (nums, k) => {
  let n = nums.length, counts = new Array(n + 1).fill(0).fill(1, 0, 1), oddCount = 0, result = 0
  for (let i = 0; i < n; i++) {
    oddCount += nums[i] & 1
    result += oddCount >= k ? counts[oddCount - k] : 0
    counts[oddCount] += 1
  }
  return result
}

var b = {
    a: function() {
        console.log(this);
    }
}
b.a();
// this is b

b.a.call(this); // this is window

function B() { 
    this.a = function() {console.log(this.b)}, 
    this.b = 1
}
let b = new B();
b.a();
// this is b object;

var a = 1;
this.a;