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…

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…

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) (…

题目大概说给一个数字组成的字符串问有几个子串其代表的数字(可以有前导0)能被4整除. dp[i][m]表示字符串0...i中mod 4为m的后缀的个数 通过在i-1添加str[i]字符转移,或者以str[i]为新后缀的开头转移 #include<cstdio> #include<cstring> using namespace std; ]; ][]; int main(){ scanf("%s",str); ; str[i]; ++i){ ++d[i][(st…

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;…

CodeForces 343A 这是第一题,像这种水题一定不要想复杂,思路不对立马换. 抓住串联和并联,可以用辗转相除法 #include <iostream> #include <string> #include <cstring> #include <cstdlib> #include <cstdio> #include <cmath> #include <algorithm> #include <stack&g…

B. New Skateboard 题目连接: http://www.codeforces.com/contest/628/problem/A Description 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 calculator on the floor and went to ask som…

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…