题目链接:http://codeforces.com/contest/628/problem/B 题目大意:给你一段数字串s(1?≤?|s|?≤?3·10^5),求该字符串有多少子串是4的倍数.解题思路:很容易可以想到,如果一个两位数可以被4整除,那么在它左边加任何数字都能被4整除,如24能被4整除,那么124,1324也可以.因为第3位就是百位,只要是100的倍数肯定也是4的倍数.所以只用考虑前两位即可. 代码: #include<bits/stdc++.h> #define lc(a) (…

CD 628B 题目大意:给定一个数字(<=3*10^5),判断其能被4整除的连续子串有多少个 解题思路:注意一个整除4的性质: 若bc能被4整除,则a1a2a3a4...anbc也一定能被4整除: 利用这个性质,先特判第一位数字是否能被4整除,可以则++cnt, 之后从第二位数字开始,设当前位为i,先判断a[i]能否被4整除,可以则++cnt, 再判断a[i-1]*10+a[i]能否被4整除,可以则cnt = cnt + (i) 相关证明: 设一整数各个位置为a1,a2,a3,...,an,b…

B. New Skateboard time limit per test 1 second memory limit per test 256 megabytes input standard input output standard output Max wants to buy a new skateboard. He has calculated the amount of money that is needed to buy a new skateboard. He left a…

New Skateboard time limit per test 1 second memory limit per test 256 megabytes input standard input output standard output Max wants to buy a new skateboard. He has calculated the amount of money that is needed to buy a new skateboard. He left a cal…

B. New Skateboard time limit per test 1 second memory limit per test 256 megabytes input standard input output standard output Max wants to buy a new skateboard. He has calculated the amount of money that is needed to buy a new skateboard. He left a…

开始填坑_(:з」∠)_ 628A - Tennis Tournament    20171124 小学数学题,\((x,y)=((n-1)\cdot(2b+1),np)\) #include<stdlib.h> #include<stdio.h> #include<math.h> #include<cstring> #include<iostream> #include<algorithm> using namespace std;…

题意 给出一个二进制数\(n\),每次操作可以将一个整数\(x\)简化为\(x\)的二进制表示中\(1\)的个数,如果一个数简化为\(1\)所需的最小次数为\(k\),将这个数叫做特殊的数, 问从\(1\)到\(n\)一共有多少个特殊的数,答案对\(1e9+7\)取模. 分析 \(n\)最大为\(2^{1000}\),二进制表示中最多有\(1000\)个\(1\),所以\(n\)以内的数经过一次简化后将变为\(1000\)以内的数,我们可以暴力打表\(1000\)以内的数简化为\(1\)所需的最…

B. New Skateboard time limit per test 1 second memory limit per test 256 megabytes input standard input output standard output Max wants to buy a new skateboard. He has calculated the amount of money that is needed to buy a new skateboard. He left a…

题目描述: Little Elephant and Interval time limit per test 2 seconds memory limit per test 256 megabytes input standard input output standard output The Little Elephant very much loves sums on intervals. This time he has a pair of integers l and r (l ≤ r…

剑指 Offer 43. 1-n 整数中 1 出现的次数 Offer_43 题目描述 题解分析 java代码 package com.walegarrett.offer; /** * @Author WaleGarrett * @Date 2021/2/8 9:29 */ /** * 题目详情: * 输入一个整数 n ,求1-n这n个整数的十进制表示中1出现的次数. * 例如,输入12,1-12这些整数中包含1 的数字有1.10.11和12,1一共出现了5次. */ public class O…