题目地址:http://acm.sgu.ru/problem.php?contest=0&problem=107 /* 题意:n位数的平方的后面几位为987654321的个数 尼玛,我看描述这一句话都看了半天,其实只要先暴力程序测试一边就知道规律 详细解释:http://www.cnblogs.com/Rinyo/archive/2012/12/04/2802089.html */ #include <cstdio> #include <iostream> #include…

题目链接: http://acm.sgu.ru/problem.php?contest=0&problem=107 题意: 平方后几位为987654321的n位数有多少个 分析: 虽然说是水题,但是我觉得很好体现了做某些数学题的方法,就是找规律 暴力求出一些较小的数,然后其他位数的数就是在求出的数的前面填数就好了. 然后注意位数很多,所以以字符的形式输出0. 代码: #include<cstdio> int main (void) { int n; scanf("%d&quo…

987654321 problem Problem's Link Mean: 略 analyse: 这道题目是道简单题. 不过的确要好好想一下: 通过简单的搜索可以知道,在N<9时答案一定为0,而N=9时有8个解.由于题目只是问“最后9位”,所以N=10的时侯第10位的取值不会对平方和的“最后9位”产生影响,而第10位上有9种取值方法,所以N=10的时侯,答案是72. 同样可以知道,当N>10的时侯,只要在72后加入(N-10)个“0”即可. Time complexity: O(n) vie…

其实挺水的,因为两个数平方,只有固定的后面几位数会影响到最后结果的后面几位数.也就是说,如果想在平方之后尾数为987654321,那么就有固定的几个尾数在平方后会是这个数,打个表,发现 10^8 内 没有,10^9 内只有 8 个,然后排列组合…… 上代码: #include <cstdio> #include <cstring> #include <cstdlib> #include <cstring> using namespace std; typed…

Another Rock-Paper-Scissors Problem 题目连接: http://codeforces.com/gym/100015/attachments Description Sonny uses a very peculiar pattern when it comes to playing rock-paper-scissors. He likes to vary his moves so that his opponent can't beat him with hi…

/** 题目:Joseph's Problem 链接:https://vjudge.net/problem/UVA-1363 题意:给定n,k;求k%[1,n]的和. 思路: 没想出来,看了lrj的想法才明白. 我一开始往素数筛那种类似做法想. 想k%[1,n]的结果会有很多重复的,来想办法优化. 但没走通. 果然要往深处想. 通过观察数据发现有等差数列.直接观察很难确定具体规律:此处应该想到用式子往这个方向推导试一试. lrj想法: 设:p = k/i; 则:k%i = k-i*p; 容易想到…

There is sequence 1, 12, 123, 1234, ..., 12345678910, ... . Given first N elements of that sequence. You must determine amount of numbers in it that are divisible by 3. Input Input contains N (1<=N<=231 - 1). Output Write answer to the output. Sampl…

题目链接: http://codeforces.com/gym/101194/attachments https://icpcarchive.ecs.baylor.edu/index.php?option=com_onlinejudge&Itemid=8&page=show_problem&problem=5919 题意: 给出正整数 $N(1 \le N \le 10^5)$,询问对于正整数 $k$,有多少个小于 $2^N$ 的 $2^k-1$ 是 $7$ 的整数倍. 题解: $…

107. 987654321 problem time limit per test: 0.25 sec. memory limit per test: 4096 KB For given number N you must output amount of N-digit numbers, such, that last digits of their square is equal to 987654321. Input Input contains integer number N (1<…

107. 987654321 problem time limit per test: 0.25 sec. memory limit per test: 4096 KB For given number N you must output amount of N-digit numbers, such, that last digits of their square is equal to 987654321. Input Input contains integer number N (1<…