[NOIP2016]换教室 期望dp

先弗洛伊德，然后把状态拆分遗传

#include<iostream>
#include<cstdio>
#include<cstring>
#include<cstdlib>
#define f(a,b,c) g[a+10][b+10][c+1]
#define N 2100
#define M 320
using namespace std;
typedef double D;
int d[M][M],c[N][];
D g[N][N][];
int n,m,v,e;
D w[N];
inline int MIN(int x,int y)
{
  return x<y?x:y;
}
inline D Min(D x,D y)
{
  return x<y?x:y;
}
int main()
{
  freopen("classrooma.in","r",stdin);
  freopen("classrooma.out","w",stdout);
  scanf("%d%d%d%d",&n,&m,&v,&e);
  for(int i=;i<=n;i++)
   scanf("%d",&c[i][]);
  for(int i=;i<=n;i++)
   scanf("%d",&c[i][]);
  for(int i=;i<=n;i++)
   scanf("%lf",&w[i]);
  memset(d,0x3f,sizeof(d));
  for(int i=;i<=v;i++)
   d[i][i]=;
  for(int i=;i<=e;i++)
  {
    int x,y,z;
    scanf("%d%d%d",&x,&y,&z);
    d[y][x]=d[x][y]=MIN(d[x][y],z);
  }
  for(int k=;k<=v;k++)
   for(int i=;i<=v;i++)
    for(int j=;j<=v;j++)
     d[i][j]=MIN(d[i][j],d[i][k]+d[k][j]);
  for(int i=;i<N;i++)
   for(int j=;j<N;j++)
    for(int k=;k<;k++)
     g[i][j][k]=2000000000.00;
  f(,,)=;
  if(m)f(,,)=;
  for(int i=;i<=n;i++)
  {
   f(i,,)=f(i-,,)+d[c[i-][]][c[i][]];
   for(int j=;j<=m;j++)
   {
     f(i,j,)=Min(f(i-,j,)+d[c[i-][]][c[i][]],f(i-,j,)+w[i-]*d[c[i-][]][c[i][]]+(1.0-w[i-])*d[c[i-][]][c[i][]]);
     f(i,j,)=f(i-,j-,)+w[i]*w[i-]*d[c[i-][]][c[i][]]+(1.0-w[i])*w[i-]*d[c[i-][]][c[i][]]+(1.0-w[i])*(1.0-w[i-])*d[c[i-][]][c[i][]]+w[i]*(1.0-w[i-])*d[c[i-][]][c[i][]];
     f(i,j,)=Min(f(i,j,),f(i-,j-,)+w[i]*d[c[i-][]][c[i][]]+(1.0-w[i])*d[c[i-][]][c[i][]]);
   }
  }
  D ans=2000000000.00;
  for(int i=;i<=m;i++)
   ans=Min(ans,Min(f(n,i,),f(n,i,)));
  printf("%.2lf",ans);
  return ;
}