题目链接 题意: H * W (W,H <= 10) 的矩阵A的某个元素A[i][j],从它出发到其他点的曼哈顿距离小于等于D的所有值的和S[i][j]除上可达点的数目,构成了矩阵B.给定矩阵B,求矩阵A. 分析: 将所有矩阵A的元素看成自变量,一共有H*W个变量,每个矩阵B的元素是由这些变量组合而成的,对于固定的B[i][j],曼哈顿距离在D以内的A[x][y]的系数为1,其它为0,这样就变成了求H*W个变量和H*W个方程的线性方程组,高斯消元求解.这题数据量比较小,所以直接采用浮点数的高斯消…

题意: H * W (W,H <= 10) 的矩阵A的某个元素A[i][j],从它出发到其他点的曼哈顿距离小于等于D的所有值的和S[i][j]除上可达点的数目,构成了矩阵B.给定矩阵B,求矩阵A. 题目先给宽再给高...坑我了一个小时 code /* 暴力确定每个位置有到那些位置的曼哈顿距离小于D 然后对你n*m个未知数,n*m个方程进行高斯消元 */ #include <iostream> #include <cstdio> #include <cmath> #…

Zhu and 772002 题目链接: http://acm.hdu.edu.cn/showproblem.php?pid=5833 Description Zhu and 772002 are both good at math. One day, Zhu wants to test the ability of 772002, so he asks 772002 to solve a math problem. But 772002 has a appointment with his g…

http://acm.hdu.edu.cn/showproblem.php?pid=5955 题意:给你长度为l的n组数,每个数1-6,每次扔色子,问你每个串第一次被匹配的概率是多少 题解:先建成ac自动机构造fail数组,然后因为fail指针可能向前转移所以不能不能直接递推dp,需要高斯消元解方程,对于节点i,假设不是结束点而且能转移到它的点有a1,a2...an,那么dp[i]=1/6*dp[a1]+1/6*dp[a2]+...+1/6*a[n],然后我们可以列出n个方程,高斯消元然后找到每…

题目链接 题意 : 给你n个数,让你从中挑K个数(K<=n)使得这k个数异或的和小于m,问你有多少种异或方式满足这个条件. 思路 : 正解据说是高斯消元.这里用DP做的,类似于背包,枚举的是异或的和,给定的数你可以选择放或者不放,dp[i][j]代表的是前 i 个数中选择k个异或的和为j. #include <stdio.h> #include <string.h> #include <iostream> #define LL long long using na…

题目链接 题意:给定n个数,这n个数的素因子值不超过2000,从中取任意个数使其乘积为完全平方数,问有多少种取法. 题解:开始用素筛枚举写了半天TLE了,后来队友说高斯消元才想起来,果断用模板.赛后又得知这是个原题sgu200,真坑啊.把每个数进行素因子分解,素因子a的幂为奇数则视为1,偶数则视为0,转化为从n个数中取数异或和为0有多少种取法的问题. AC代码: #include <cstdio> #include <cstring> #include <cmath>…

建立方程后消元 #include<cstdio> #include<iostream> #include<cstdlib> #include<cstring> #include<string> #include<algorithm> #include<map> #include<queue> #include<vector> #include<cmath> #include<uti…

题意:给n个数,从n个数中抽取x(x>=1)个数,这x个数相乘为完全平方数,求一共有多少种取法,结果模1000000007. 思路:每个数可以拆成素数相乘的形式,例如: x1 2=2^1 * 3^0 * 5^0; x2 3=2^0 * 3^1 * 5^0; x3 4=2^2 * 3^0 * 5^0; x4 5=2^0 * 3^0 * 5^1; x5 6=2^1 * 3^1 * 5^0; x6 15=2^0 * 3^1 * 5^1; 用xi表示第i个数选或不选,xi的取值为0或1:因为相乘结果为完…

Crazy Typewriter Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 32768/32768 K (Java/Others)Total Submission(s): 391    Accepted Submission(s): 109 Problem Description There was a crazy typewriter before. When the writer is not very sober, it…

Ba Gua Zhen Problem Description During the Three-Kingdom period, there was a general named Xun Lu who belonged to Kingdom Wu. Once his troop were chasing Bei Liu, he was stuck in the Ba Gua Zhen from Liang Zhuge. The puzzle could be considered as an…