Educational Codeforces Round 53 E. Segment Sum 题意: 问[L,R]区间内有多少个数满足:其由不超过k种数字构成. 思路: 数位DP裸题,也比较好想.由于没考虑到前导0,卡了很久.但最惨的是,由于每次求和的时候需要用到10的pos次幂,我是用提前算好的10的最高次幂,然后每次除以10往下传参.但我手贱取模了,导致每次除以10之后答案就不同余了,这个NC细节错误卡了我一小时才发现. 代码: #include<iostream> #include<…

D. Magic Numbers 题目连接: http://www.codeforces.com/contest/628/problem/D Description Consider the decimal presentation of an integer. Let's call a number d-magic if digit d appears in decimal presentation of the number on even positions and nowhere els…

这场比赛没有打,后来补了一下,第五题数位dp好不容易才搞出来(我太菜啊). 比赛传送门:http://codeforces.com/contest/1073 A. Diverse Substring 题意:给你个字符串,让你找一个子串满足任意一个字符的个数不超过其他字符的总和,输出yes或no表示否存在,如果存在输出任意一个. 这题只要找两个不同的相邻字符,因为两个字符各一个都不超过其他字符的总和,如果字符串只由一个字符组成或长度等于一才会不存在. 代码如下: #include <iostrea…

题目链接:https://codeforces.com/contest/1073/problem/E 题目大意:给定一个区间[l,r],需要求出区间[l,r]内符合数位上的不同数字个数不超过k个的数的和(并且模998244353) 例如求区间[10,50],k=1,答案为ans=(11+22+33+44)%998244353=110. Examples input Copy 10 50 2 output Copy 1230 input Copy 1 2345 10 output Copy 275…

https://codeforces.com/contest/1073/problem/E 题意 求出l到r之间的符合要求的数之和,结果取模998244353 要求:组成数的数位所用的数字种类不超过k种 思路 这题一看就是个数位dp的模板题,但是由于以前没有完全理解数位dp加上xjb套模版,导致样例都没算出来 一开始这样定义状态 dp[i][j] 代表第cnt-i(高位到低位)位,cnt~i状态为j的总和 一直记录当前数字的数值,到边界的时候返回加到答案中,但是由于这样定义状态会导致一个状态对应…

http://codeforces.com/contest/1073 A. Diverse Substring #include <bits/stdc++.h> using namespace std; #define ll long long #define minv 1e-6 #define inf 1e9 #define pi 3.1415926536 #define nl 2.7182818284 ; ; char s[maxn]; int main() { int n,i; scan…

A:差点开场懵逼.只要有相邻两位不同就可以作为答案. #include<iostream> #include<cstdio> #include<cmath> #include<cstdlib> #include<cstring> #include<algorithm> using namespace std; int read() { ,f=;char c=getchar(); ;c=getchar();} )+(x<<)…

A. Tricky Sum Time Limit: 20 Sec Memory Limit: 256 MB 题目连接 http://codeforces.com/contest/598/problem/A Description In this problem you are to calculate the sum of all integers from 1 to n, but you should take all powers of two with minus in the sum.…

After I read the solution to the problem, I found that my solution was simply unsightly. Solved 4 out of 7, and my solution to C was hacked, because of my incorrect order when i meet in the middle. I wasted about 20 mins on problem A due to the incom…

F. The Sum of the k-th Powers 题目连接: http://www.codeforces.com/contest/622/problem/F Description There are well-known formulas: , , . Also mathematicians found similar formulas for higher degrees. Find the value of the sum modulo 109 + 7 (so you shoul…