poj 3071 Football 概率DP

概率DP，递推式：dp[i][j]=sigma(dp[i-1][j]*p[j][k]*dp[i-1][k])

再就是判断j和k是否相邻：if(((k>>(i-1))^1)==(j>>(i-1)))

代码如下：

#include<iostream>
#include<stdio.h>
#include<algorithm>
#include<iomanip>
#include<cmath>
#include<cstring>
using namespace std;
double dp[129][129],p[129][129];
int main()
{
int i,j,k,ans,n;
while(cin>>n){
if(n==-1) break;
for(i=0;i<(1<<n);i++)
for(j=0;j<(1<<n);j++){
cin>>p[i][j];
}
memset(dp,0,sizeof(dp));
for(i=0;i<(1<<n);i++) dp[0][i]=1;
for(i=1;i<=n;i++)
for(j=0;j<(1<<n);j++)
for(k=0;k<(1<<n);k++){
if(((k>>(i-1))^1)==(j>>(i-1)))
dp[i][j]+=dp[i-1][j]*dp[i-1][k]*p[j][k];
}
ans=0;
for(i=0;i<(1<<n);i++)
if(dp
[i]>dp
[ans])
ans=i;
cout<<ans+1<<endl;
}
}

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