BNUOJ 52517 Another Server

#include<bits/stdc++.h>

using namespace std;

const int maxn =  + ;

const int INF = 0x7FFFFFFF;

struct Edge

{

    int from, to, cap, flow;

    Edge(int u, int v, int c, int f) :from(u), to(v), cap(c), flow(f){}

};

vector<Edge>edges;

vector<int>G[maxn];

bool vis[maxn];

int d[maxn];

int cur[maxn];

int n, s, t;

void init()

{

    for (int i = ; i < maxn; i++)

        G[i].clear();

    edges.clear();

}

void AddEdge(int from, int to, int cap)

{

    edges.push_back(Edge(from, to, cap, ));

    edges.push_back(Edge(to, from, , ));

    int w = edges.size();

    G[from].push_back(w - );

    G[to].push_back(w - );

}

bool BFS()

{

    memset(vis, , sizeof(vis));

    queue<int>Q;

    Q.push(s);

    d[s] = ;

    vis[s] = ;

    while (!Q.empty())

    {

        int x = Q.front();

        Q.pop();

        for (int i = ; i<G[x].size(); i++)

        {

            Edge e = edges[G[x][i]];

            if (!vis[e.to] && e.cap>e.flow)

            {

                vis[e.to] = ;

                d[e.to] = d[x] + ;

                Q.push(e.to);

            }

        }

    }

    return vis[t];

}

int DFS(int x, int a)

{

    if (x == t || a == )

        return a;

    int flow = , f;

    for (int &i = cur[x]; i<G[x].size(); i++)

    {

        Edge e = edges[G[x][i]];

        if (d[x]+ == d[e.to]&&(f=DFS(e.to,min(a,e.cap-e.flow)))>)

        {

            edges[G[x][i]].flow+=f;

            edges[G[x][i] ^ ].flow-=f;

            flow+=f;

            a-=f;

            if(a==) break;

        }

    }

    if(!flow) d[x] = -;

    return flow;

}

int dinic(int s, int t)

{

    int flow = ;

    while (BFS())

    {

        memset(cur, , sizeof(cur));

        flow += DFS(s, INF);

    }

    return flow;

}

int T;

int main()

{

    scanf("%d",&T);

    while(T--)

    {

        scanf("%d",&n);

        init();

        s=; t=n;

        for(int i=;i<=*n-;i++)

        {

            int x; scanf("%d",&x);

            AddEdge((i+)/,(i+)/+,x);

        }

        printf("%d\n",dinic(s,t));

    }

    return ;

}