摘要：
Let f(x) be the number of zeroes at the end of x!. (Recall that x! = 1 * 2 * 3 * ... * x, and by convention, 0! = 1.) For example, f(3) = 0 because 3! 阅读全文
摘要：
We are given an array A of positive integers, and two positive integers L and R (L <= R). Return the number of (contiguous, non-empty) subarrays such 阅读全文
摘要：
Given string S and a dictionary of words words, find the number of words[i] that is a subsequence of S. Note: All words in words and S will only consi 阅读全文
摘要：
A Tic-Tac-Toe board is given as a string array board. Return True if and only if it is possible to reach this board position during the course of a va 阅读全文