题目2 : Dice Possibility
时间限制: 10000ms 单点时限: 1000ms 内存限制: 256MB
-
2 10
样例输出 -
8.33
描述
What is possibility of rolling N dice and the sum of the numbers equals to M?输入
Two integers N and M. (1 ≤ N ≤ 100, 1 ≤ M ≤ 600)输出
Output the possibility in percentage with 2 decimal places.
样例输入
题意:用N个骰子扔出总点数为M的概率是多少。
题解:概率DP。dp[i][j]表示扔 i 个骰子,点数为 j 的概率。
AC代码:
#include<bits/stdc++.h>
using namespace std;
int main()
{
int N,M;
double dp[101][601] = {0};
cin >>N>>M;
for (int i = 1; i <= 6; i++)
{
dp[1][i]=(1.0/6);
}
for (int i = 2; i <= N; i++)
{
for (int j = i; j <=M; j++)
{
if(j-i<6)
{
for(int k = i-1;k<j;k++)
{
dp[i][j] += dp[i-1][k]/6;
}
}
else
{
for(int k =j-6;k<j;k++)
{
dp[i][j] += dp[i-1][k]/6;
}
}
}
}
printf("%.2lf\n",dp[N][M]*100);
return 0;
}