HDU4183最大流

题目链接

---

http://acm.hdu.edu.cn/showproblem.php?pid=4183
 o(n^2)暴力连边然后有要求每个点跑一次，那么只要让其容量为1即可。

#include <bits/stdc++.h>

using namespace std;
const int maxn = 350;
const int INF = 0x3f3f3f3f;
struct Edge
{
    int from, to;
    int cap, flow;
    Edge(int from, int to, int cap, int flow):from(from), to(to), cap(cap), flow(flow){}
};
struct EdmondsKarp
{
    vector<Edge> edges;
    vector<int>G[maxn];
    int a[maxn];
    int p[maxn];
    void init(int n)
    {
        for(int i = 0;i <= n;i++)
            G[i].clear();
        edges.clear();
    }
    void AddEdge(int from, int to, int cap)
    {
        edges.push_back(Edge(from, to, cap, 0));
        edges.push_back(Edge(to, from, 0, 0));
        int m = edges.size();
        G[from].push_back(m - 2);
        G[to].push_back(m - 1);
    }
    int Maxflow(int s, int t)
    {
        int flow = 0;
        for(;;)
        {
            memset(a, 0, sizeof(a));
            queue<int>Q;
            Q.push(s);
            a[s] = INF;
            while(!Q.empty())
            {
                int x = Q.front();
                Q.pop();
                for(int i = 0;i < (int)G[x].size();i++)
                {
                    Edge &e = edges[G[x][i]];
                    if(!a[e.to]&&e.cap > e.flow)
                    {
                        p[e.to] = G[x][i];
                        a[e.to] = min(a[x], e.cap - e.flow);
                        Q.push(e.to);
                    }
                }
                if(a[t])
                    break;
            }
            if(!a[t])
                break;
            for(int u = t;u != s;u = edges[p[u]].from)
            {
                edges[p[u]].flow += a[t];
                edges[p[u]^1].flow -= a[t];
            }
            flow += a[t];
        }
        return flow;
    }
}ek;
struct Node
{
    double hz, x, y, v;
}node[maxn];
double d(Node a, Node b)
{
    return sqrt((a.x - b.x) * (a.x - b.x) + (a.y - b.y) * (a.y - b.y));
}
bool cmp(Node x,Node y){
    if(x.hz<y.hz)
        return true;
    return false;
}
int main()
{
    int t;
    scanf("%d", &t);
    while(t--)
    {
        int n;
        cin>>n;
        ek.init(n);
        for(int i = 1;i <= n;i++)
        {
            cin>>node[i].hz>>node[i].x>>node[i].y>>node[i].v;
        }
        sort(node + 1, node + 1 + n, cmp);
        for(int i = 1;i <= n;i++)
        {
            for(int j = i + 1;j <= n;j++)
            {
                if(d(node[i], node[j]) <= node[i].v + node[j].v&&node[i].hz < node[j].hz)
                {
                    ek.AddEdge(i, j, 1);
                }
            }
        }
        int ans = ek.Maxflow(1, n);
        if(ans >= 2)
            printf("Game is VALID\n");
        else
        printf("Game is NOT VALID\n");
    }
    return 0;
}