题目链接 http://acm.hdu.edu.cn/showproblem.php?pid=4990 题意 初始的ans = 0 给出 n, m for i in 1 -> n 如果 i 为奇数 ans = (ans * 2 + 1) % m 反之 ans = ans * 2 % m 思路 如果我们只计算 偶数项 那么递推公式就是 ans[n] = 4 * ans[n - 2] + 2 如果 n 是偶数 那么刚好 就按这个公式推 第 n / 2 项 如果 n 是奇数 那么就是 第 [ n /…

题目链接:pid=4990" style="color:rgb(255,153,0); text-decoration:none; font-family:Arial; line-height:26px">http://acm.hdu.edu.cn/showproblem.php?pid=4990 思路:曾经有一个矩阵乘法的做法请戳这儿.. . . 開始我们把数都不模... 能够得到一个规律 n:1        ans:1      4^0             …

Description Read the program below carefully then answer the question. #pragma comment(linker, "/STACK:1024000000,1024000000") #include <cstdio> #include<iostream> #include <cstring> #include <cmath> #include <algorith…

题意:给一串数字,问长度为m的严格上升子序列有多少个 解法:首先可以离散化为10000以内,再进行dp,令dp[i][j]为以第i个元素结尾的长度为j的上升子序列的个数, 则有dp[i][j] = SUM(dp[k][j-1])  (a[k] < a[i] && k < i) 不可能直接遍历,所以考虑优化,可以看出dp方程相当于一个区间求和,所以可以用树状数组来优化. 代码: #include <iostream> #include <cmath> #i…

快速幂 #include<cstdio> #include<cstring> #include<cmath> #include<iostream> #include<algorithm> using namespace std; long long n,MOD; long long cal(long long a,long long b,long long mod) { ; ) { ==) c=(c*a)%mod,b--; ; } return…

Read the program below carefully then answer the question. #pragma comment(linker, "/STACK:1024000000,1024000000") #include <cstdio> #include<iostream> #include <cstring> #include <cmath> #include <algorithm> #inclu…

思路: 如图找到推导公式,然后一通乱搞就好了 要开long long,否则红橙作伴 代码: #include<set> #include<cstring> #include<cstdio> #include<algorithm> #define ll long long const int maxn = 3; const int MOD = 1000000000+7; const int INF = 0x3f3f3f3f; using namespace s…

Problem Description Read the program below carefully then answer the question.#pragma comment(linker, "/STACK:1024000000,1024000000")#include <cstdio>#include<iostream>#include <cstring>#include <cmath>#include <algori…

;i<=n;i++) { )ans=(ans*+)%m; %m; } 给定n,m.让你用O(log(n))以下时间算出ans. 打表,推出 ans[i] = 2^(i-1) + f[i-2] 故 i奇数:ans[i] = 2^(i-1) + 2^(i-3) ... + 1; i偶数:ans[i] = 2^(i-1) + 2^(i-3) ... + 2; 故可以用等比数列求和公式. 公式涉及除法.我也没弄懂为啥不能用逆元,貌似说是啥逆元可能不存在. 所以a/b % m == a%(b*m) / b…

Reading comprehension Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 32768/32768 K (Java/Others)Total Submission(s): 1270    Accepted Submission(s): 512 Problem Description Read the program below carefully then answer the question.#pragma co…