The specifications of square tiles are unlimited, and the side lengths are all integers. Can you help the designer calculate the minimum number of square tiles needed? There are two characters of the same length, and you need to make these two strings the same by "exchanging characters"; Here is an integer array and an integer k. If there are exactly k odd numbers in a continuous subarray, return the number of Youmei subarrays in this array; To give you a positive integer array, you need to select any subset from it, then multiply each number in the subset by an arbitrary integer, and find their sum.