【BZOJ-2055】80人环游世界 上下界费用流 （无源无汇最小费用最大流）

#include<iostream>
#include<cstdio>
#include<algorithm>
#include<cstring>
#include<cmath>
#include<queue>
using namespace std;
int read()
{
    int x=0,f=1; char ch=getchar();
    while (ch<‘0‘ || ch>‘9‘) {if (ch==‘-‘) f=-1; ch=getchar();}
    while (ch>=‘0‘ && ch<=‘9‘) {x=x*10+ch-‘0‘; ch=getchar();}
    return x*f;
}
#define maxn 500
#define maxm 1000010
int n,m,v[maxn],co[110][110],MinCost;
struct EdgeNode{int next,to,from,cap,cost;}edge[maxm];
int head[maxn],ind[maxn],cnt=1,from[maxn];
void add(int u,int v,int w,int c)
{
    cnt++;
    edge[cnt].cap=w; edge[cnt].to=v; edge[cnt].from=u; edge[cnt].next=head[u]; head[u]=cnt; edge[cnt].cost=c;
}
void insert(int u,int v,int w,int c) {add(u,v,w,c); add(v,u,0,-c);}
int dis[maxn],S,T; bool mark[maxn]; queue<int>q;
#define inf 0x7fffffff
bool spfa()
{
    memset(mark,0,sizeof(mark));
    for (int i=0; i<=T; i++) dis[i]=inf;
    q.push(0); dis[0]=0; mark[0]=1;
    while (!q.empty())
        {
            int now=q.front(); q.pop(); mark[now]=0;
            for (int i=head[now]; i; i=edge[i].next)
                if (edge[i].cap && dis[edge[i].to]>dis[now]+edge[i].cost )
                    {
                        dis[edge[i].to]=dis[now]+edge[i].cost; from[edge[i].to]=i;
                        if (!mark[edge[i].to])
                            q.push(edge[i].to),mark[edge[i].to]=1;
                    }
        }
    return dis[T]!=inf;
}
void MCMF()
{
    int flow=inf;
    for (int i=from[T]; i; i=from[edge[i].from])
        flow=min(flow,edge[i].cap);
    for (int i=from[T]; i; i=from[edge[i].from])
        edge[i].cap-=flow,edge[i^1].cap+=flow,MinCost+=flow*edge[i].cost;    
}
void Build()
{
    S=2*n+1,T=2*n+2;
    for (int i=1; i<=n; i++) insert(i,i+n,0,0),ind[i]-=v[i],ind[i+n]+=v[i];
    insert(0,S,m,0);
    for (int i=1; i<=n; i++) insert(S,i,inf,0);
    for (int i=1; i<n; i++)
        for (int j=i+1; j<=n; j++)
            if (co[i][j]!=-1) insert(i+n,j,inf,co[i][j]);
    
    for (int i=1; i<=2*n; i++)
        if (ind[i]>0) insert(0,i,ind[i],0);
            else insert(i,T,-ind[i],0);    
}
int main()
{
    n=read(),m=read();
    for (int i=1; i<=n; i++) v[i]=read();
    for (int i=1; i<n; i++)
        for (int j=i+1; j<=n; j++)
            co[i][j]=read();
    Build();
    while (spfa()) MCMF();
    printf("%d\n",MinCost);
    return 0;
}