bzoj4873: [Shoi2017]寿司餐厅

#include<cstdio>
#include<iostream>
#include<cstring>
#include<cstdlib>
#include<algorithm>
#include<cmath>
using namespace std;
const int inf=(1<<30)-1;

struct node
{
    int x,y,c,next;
}a[210000];int len,last[11000];
void ins(int x,int y,int c)
{
    len++;
    a[len].x=x;a[len].y=y;a[len].c=c;
    a[len].next=last[x];last[x]=len;
    
    len++;
    a[len].x=y;a[len].y=x;a[len].c=0;
    a[len].next=last[y];last[y]=len;
}
int h[11000],st,ed;
int list[11000];
bool bt_h()
{
    memset(h,0,sizeof(h));h[st]=1;
    int head=1,tail=2;list[1]=st;
    while(head!=tail)
    {
        int x=list[head];
        for(int k=last[x];k;k=a[k].next)
        {
            int y=a[k].y;
            if(a[k].c>0&&h[y]==0)
            {
                h[y]=h[x]+1;
                list[tail++]=y;
            }
        }
        head++;
    }
    return h[ed]!=0;
}
int findflow(int x,int f)
{
    if(x==ed)return f;
    int s=0;
    for(int k=last[x];k;k=a[k].next)
    {
        int y=a[k].y;
        if(a[k].c>0&&h[y]==h[x]+1&&s<f)
        {
            int t=findflow(y,min(a[k].c,f-s));
            s+=t;a[k].c-=t;a[k^1].c+=t;
        }
    }
    if(s==0)h[x]=0;
    return s;
}

//---------------------------------findflow---------------------------------------------------

int tap[110],mp[110][110];
int z,id[1100],mid[110][110];
int main()
{
    int n,m;
    scanf("%d%d",&n,&m); z=n;
    for(int i=1;i<=n;i++)
    {
        scanf("%d",&tap[i]);
        if(id[tap[i]]==0)id[tap[i]]=++z;
    }
    for(int i=1;i<=n;i++)
        for(int j=i;j<=n;j++)
            scanf("%d",&mp[i][j]),mid[i][j]=++z;
            
    //...........read.............
            
    st=++z,ed=++z; len=1;
    for(int i=1;i<=1000;i++)
        if(id[i])ins(st,id[i],m*i*i);
    for(int i=1;i<=n;i++)
        ins(id[tap[i]],i,inf),ins(st,i,tap[i]);
    int sum=0;
    for(int i=1;i<=n;i++)
        for(int j=i;j<=n;j++)
        {
            if(i==j)ins(i,mid[i][j],inf);
            else ins(mid[i+1][j],mid[i][j],inf),ins(mid[i][j-1],mid[i][j],inf);
            
            if(mp[i][j]>=0)ins(mid[i][j],ed,mp[i][j]),sum+=mp[i][j];
            else ins(st,mid[i][j],-mp[i][j]);
        }    
    
    //......composition............
    
    int ans=0;
    while(bt_h())
    {
        ans+=findflow(st,inf);
    }
    printf("%d\n",sum-ans);
    
    return 0;
}