洛谷P1850 换教室

洛谷P1850 换教室

原题链接

// It is made by XZZ
#include<cstdio>
#include<algorithm>
#include<cmath>
using namespace std;
#define rep(a,b,c) for(rg int a=b;a<=c;a++)
#define drep(a,b,c) for(rg int a=b;a>=c;a--)
#define erep(a,b) for(rg int a=fir[b];a;a=nxt[a])
#define il inline
#define rg register
#define vd void
#define db double
typedef long long ll;
il int gi(){
rg int x=0,f=1;rg char ch=getchar();
while(ch<'0'||ch>'9')f=ch=='-'?-1:f,ch=getchar();
while(ch>='0'&&ch<='9')x=x*10+ch-'0',ch=getchar();
return x*f;
}
db u[302][302];
db f[2010][2010],g[2010][2010];
int c[2002],d[2002];
db k[2002];
int main(){
// freopen("classrooma.in","r",stdin);
// freopen("classrooma.out","w",stdout);
int n=gi(),m=gi(),v=gi(),e=gi();
rep(i,1,n)c[i]=gi();rep(i,1,n)d[i]=gi();
rep(i,1,n)scanf("%lf",&k[i]);
rep(i,1,v)rep(j,i+1,v)u[i][j]=u[j][i]=1e9;
{
int a,b;db c;
while(e--){
a=gi(),b=gi();
scanf("%lf",&c);
u[a][b]=u[b][a]=min(u[a][b],c);
}
}
rep(l,1,v)rep(i,1,v)rep(j,1,v)u[i][j]=min(u[i][j],u[i][l]+u[j][l]);
rep(i,0,n)rep(j,0,m)f[i][j]=g[i][j]=1e9;
f[1][0]=g[1][1]=0;
rep(i,2,n){
f[i][0]=f[i-1][0]+u[c[i-1]][c[i]];
rep(j,1,min(m,i)){
f[i][j]=min(
f[i-1][j]+
u[c[i-1]][c[i]],

g[i-1][j]+
k[i-1]*u[d[i-1]][c[i]]+
(1.0-k[i-1])*u[c[i-1]][c[i]]
);
g[i][j]=min(
f[i-1][j-1]+
k[i]*u[c[i-1]][d[i]]+
(1-k[i])*u[c[i-1]][c[i]],

g[i-1][j-1]+
k[i]*k[i-1]*u[d[i-1]][d[i]]+
k[i]*(1.0-k[i-1])*u[c[i-1]][d[i]]+
k[i-1]*(1.0-k[i])*u[d[i-1]][c[i]]+
(1.0-k[i])*(1.0-k[i-1])*u[c[i-1]][c[i]]
);
}
}
db ans=f
[0];
rep(i,1,m)ans=min(ans,min(f
[i],g
[i]));
printf("%.2lf\n",ans);
return 0;
}