hihocoder太阁面经算法竞赛8-Dice Possibility

hihocoder太阁面经算法竞赛8-Dice Possibility。 

题目： 

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

2 10

样例输出

8.33

这道题比较简单，使用模拟的方法，即可解决。 

#include <iostream>
#include <cstdio>
#include <cstdlib>
#include <cstring>
using namespace std;
const int maxn = 605;
const int maxm = 102;
const double min_val = 1e-9;

int n,m;
double mp[maxm][maxn];

int main(){
freopen("in.txt", "r", stdin);

int i,j,k, cnt;
while(scanf("%d %d", &n, &m) != EOF){
if(n > m || 6*n < m){
printf("%.2f\n", 0.00);
continue;
}
memset(mp, 0, sizeof(mp));
mp[0][0] = 1.0; cnt = 0;
for(i=1; i<=n; i++){
for(j=cnt; j<=6*cnt; j++){
for(k=1; k<=6; k++){
mp[i][j+k] += mp[i-1][j]*(1.0/6.0);
}
}
cnt++;
}
printf("%.2f\n", mp
[m]*100);
}
return 0;
}