ZOJ - 3822 Domination （DP）
内容导读
互联网集市收集整理的这篇技术教程文章主要介绍了ZOJ - 3822 Domination （DP），小编现在分享给大家，供广大互联网技能从业者学习和参考。文章包含2116字，纯文字阅读大概需要4分钟。
内容图文
Edward is the headmaster of Marjar University. He is enthusiastic about chess and often plays chess with his friends. What‘s more, he bought a large decorative chessboard with N rows and M columns.
Every day after work, Edward will place a chess piece on a random empty cell. A few days later, he found the chessboard was dominated by the chess pieces. That means there is at least one chess piece in every row. Also, there is at least one chess piece in every column.
"That‘s interesting!" Edward said. He wants to know the expectation number of days to make an empty chessboard of N × M dominated. Please write a program to help him.
Input
There are multiple test cases. The first line of input contains an integer T indicating the number of test cases. For each test case:
There are only two integers N and M (1 <= N, M <= 50).
Output
For each test case, output the expectation number of days.
Any solution with a relative or absolute error of at most 10-8 will be accepted.
Sample Input
2 1 3 2 2
Sample Output
3.000000000000 2.666666666667
#include <iostream>
#include <cstdio>
#include <cstring>
#include <algorithm>
#include <cmath>
using namespace std;
const int maxn = 55;
double dp[maxn*maxn][maxn][maxn];
int n, m;
int main() {
int t;
scanf("%d", &t);
while (t--) {
scanf("%d%d", &n, &m);
memset(dp, 0, sizeof(dp));
dp[1][1][1] = 1.0;
for (int i = 1; i < n*m; i++)
for (int j = 1; j <= n; j++)
for (int k = 1; k <= m; k++)
if (dp[i][j][k] > 0) {
dp[i+1][j+1][k+1] += dp[i][j][k] * (n - j) * (m - k) / (n * m - i);
dp[i+1][j+1][k] += dp[i][j][k] * (n - j) * k / (n * m - i);
dp[i+1][j][k+1] += dp[i][j][k] * j * (m - k) / (n * m - i);
if (j < n || k < m)
dp[i+1][j][k] += dp[i][j][k] * (j * k - i) / (n * m - i);
}
double ans = 0;
for (int i = 1; i <= n * m; i++)
ans += dp[i][n][m] * i;
printf("%.8lf\n", ans);
}
return 0;
}
原文：http://blog.csdn.net/u011345136/article/details/40022863
内容总结
以上是互联网集市为您收集整理的ZOJ - 3822 Domination （DP）全部内容，希望文章能够帮你解决ZOJ - 3822 Domination （DP）所遇到的程序开发问题。 如果觉得互联网集市技术教程内容还不错，欢迎将互联网集市网站推荐给程序员好友。
内容备注
版权声明：本文内容由互联网用户自发贡献，该文观点与技术仅代表作者本人。本站仅提供信息存储空间服务，不拥有所有权，不承担相关法律责任。如发现本站有涉嫌侵权/违法违规的内容， 请发送邮件至 gblab@vip.qq.com 举报，一经查实，本站将立刻删除。
内容手机端
扫描二维码推送至手机访问。