题意:nxm的棋盘,要求每行每列至少放一个棋子的方法数. 解法:首先可以明确是DP,这种行和列的DP很多时候都要一行一行的推过去,即至少枚举此行和前一行. dp[i][j]表示前 i 行有 j 列都有了棋子,且每行也有棋子. 这题做法: 从第1行到第n行,枚举这一行有k列已至少有一个,再枚举前一行有j列至少有一个,然后枚举这一行新放多少个棋子t,至少一个(因为每行至少一个) 那么有 dp[i][k] += dp[i-1][j]*C[m-j][k-j]*C[j][t-(k-j)], C表示组合数…

题目链接:HDOJ - 5155 题目大意 有一个 n * m 的棋盘,已知每行每列都至少有一个棋子,求可能有多少种不同的棋子分布情况.答案对一个大素数取模. 题目分析 算法1: 使用容斥原理与递推. 首先,一个 n * m 的棋盘不考虑任何限制时,可能的分布情况为 2^(n*m) ,除去没有棋子的情况,为 2^(n*m) - 1 . 然后,因为所有的 n 行,m 列都有棋子,所以枚举 ii (1 <= ii <= i) , jj (1 <= jj <= j) .对于枚举的一组 (…

DP.dp[i][j]可以表示i行j列满足要求的组合个数,考虑dp[i-1][k]满足条件,那么第i行的那k列可以为任意排列(2^k),其余的j-k列必须全为1,因此dp[i][j] += dp[i-1][k]*(2^k)*C(j, k). /* 5155 */ #include <cstdio> #include <cstring> #include <cstdlib> #define MAXN 51 ; __int64 dp[MAXN][MAXN]; __int64…

题目1 : Magic Box 时间限制:10000ms 单点时限:1000ms 内存限制:256MB 描述 The circus clown Sunny has a magic box. When the circus is performing, Sunny puts some balls into the box one by one. The balls are in three colors: red(R), yellow(Y) and blue(B). Let Cr, Cy, Cb…

#1135 : Magic Box 时间限制:10000ms 单点时限:1000ms 内存限制:256MB 描述 The circus clown Sunny has a magic box. When the circus is performing, Sunny puts some balls into the box one by one. The balls are in three colors: red(R), yellow(Y) and blue(B). Let Cr, Cy, C…

Harry And Magic Box Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 32768/32768 K (Java/Others)Total Submission(s): 624    Accepted Submission(s): 293 Problem Description One day, Harry got a magical box. The box is made of n*m grids. There a…

传送门 Harry And Magic Box Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 32768/32768 K (Java/Others)Total Submission(s): 165    Accepted Submission(s): 64 Problem Description One day, Harry got a magical box. The box is made of n*m grids. Ther…

题目1 : Magic Box 时间限制:10000ms 单点时限:1000ms 内存限制:256MB 描述 The circus clown Sunny has a magic box. When the circus is performing, Sunny puts some balls into the box one by one. The balls are in three colors: red(R), yellow(Y) and blue(B). Let Cr, Cy, Cb…

题目链接:https://vjudge.net/problem/HDU-5155#author=0 题意:在一个n*m的方格中要满足每一行每一列至少有一个珠宝,问总共有多少种方案. 思路:利用递推的思想:dp[i][j]表示前i行前j列满足条件的个数,那么如果说前i行前j-1列已经满足条件了那么第j列可以放[1,n]个那么dp[i][j]=dp[i][j-1]*(2^n-1);因此假设前i行j-1列有k行还没放珠宝那么 dp[i][j]=dp[i-k][j-1]*C(i,k)*(C(i-k,0)…

One day Vasya was going home when he saw a box lying on the road. The box can be represented as a rectangular parallelepiped. Vasya needed no time to realize that the box is special, as all its edges are parallel to the coordinate axes, one of its ve…