作者: 负雪明烛 id: fuxuemingzhu 个人博客: http://fuxuemingzhu.cn/ 目录 题目描述 题目大意 解题方法 动态规划 前缀和求余 日期 题目地址:https://leetcode.com/problems/subarray-sums-divisible-by-k/ 题目描述 Given an array A of integers, return the number of (contiguous, non-empty) subarrays that ha…

题目如下: Given an array A of integers, return the number of (contiguous, non-empty) subarrays that have a sum divisible by K. Example 1: Input: A = [4,5,0,-2,-3,1], K = 5 Output: 7 Explanation: There are 7 subarrays with a sum divisible by K = 5: [4, 5,…

分析 这题场上前缀和都想出来了,然后就没有然后了...哭惹.jpg 前缀和相减能够得到任意一段连续区间的和,然后他们取余\(K\)看余数是否为0就能得到.这是朴素的遍历算法.那么反过来说,如果两个前缀和都对\(K\)余\(p\),那么他们相减一定能够被K整除. 我们就这么统计就可以了,然后一个简单的求和即可.想到不难,难的是想到. 代码 class Solution { public int subarraysDivByK(int[] A, int K) { int[] prefix = new…

Given an array A of integers, return the number of (contiguous, non-empty) subarrays that have a sum divisible by K. Example 1: Input: A = [4,5,0,-2,-3,1], K = 5 Output: 7 Explanation: There are 7 subarrays with a sum divisible by K = 5: [4, 5, 0, -2…

作者: 负雪明烛 id: fuxuemingzhu 个人博客: http://fuxuemingzhu.cn/ 目录 题目描述 题目大意 解题方法 日期 题目地址:https://leetcode.com/problems/smallest-integer-divisible-by-k/ 题目描述 Given a positive integer K, you need find the smallest positive integer N such that N is divisible b…

作者: 负雪明烛 id: fuxuemingzhu 个人博客: http://fuxuemingzhu.cn/ 题目地址: https://leetcode.com/problems/subarray-product-less-than-k/description/ 题目描述: Your are given an array of positive integers nums. Count and print the number of (contiguous) subarrays where…

Given an array A of integers, return the number of (contiguous, non-empty) subarrays that have a sum divisible by K. Example 1: Input: A = [4,5,0,-2,-3,1], K = 5 Output: 7 Explanation: There are 7 subarrays with a sum divisible by K = 5: [4, 5, 0, -2…

Given an array A of integers, return the number of (contiguous, non-empty) subarrays that have a sum divisible by K. Example 1: Input: A = [4,5,0,-2,-3,1], K = 5 Output: 7 Explanation: There are 7 subarrays with a sum divisible by K = 5: [4, 5, 0, -2…

题目如下: Given a positive integer K, you need find the smallest positive integer N such that N is divisible by K, and N only contains the digit 1. Return the length of N.  If there is no such N, return -1. Example 1: Input: 1 Output: 1 Explanation: The…

前缀和(prefix sum/cumulative sum)的应用. 还用了一个知识点: a≡b(mod d) 则 a-b被d整除. 即:a与b对d同余,则a-b被d整除. class Solution(object): def subarraysDivByK(self, A, K): P = [0] for x in A: P.append((P[-1] + x) % K) count = collections.Counter(P) return sum(v*(v-1)/2 for v in…