Island Transport 【HDU

题目链接

  可以说是真的把时间卡爆了，不断的修改了好多次之后才A了，一直T一直T，哭了……

  可以说是很练时间优化了，不断的改，不断的提交，最后竟然是改了Dinic中的BFS()中，我们一旦搜索到了T之后就是直接break掉，就可以过了。还有一个优化就是在Dinic上面需要加当前弧优化操作才可以，另外不知道改出来的手动队列到最后有没有派上用处。

#pragma comment(linker, "/STACK:1024000000,1024000000")
#include <iostream>
#include <cstdio>
#include <cmath>
#include <string>
#include <cstring>
#include <algorithm>
#include <limits>
#include <vector>
#include <stack>
#include <queue>
#include <set>
#include <map>
#define lowbit(x) ( x&(-x) )
#define pi 3.141592653589793
#define e 2.718281828459045
#define INF 0x3f3f3f3f
#define HalF (l + r)>>1
#define lsn rt<<1
#define rsn rt<<1|1
#define Lson lsn, l, mid
#define Rson rsn, mid+1, r
#define QL Lson, ql, qr
#define QR Rson, ql, qr
#define myself rt, l, r
using namespace std;
typedef unsigned long long ull;
typedef long long ll;
const int maxN = 1e5 + 7;
int N, M, S, T, head[maxN], cnt, cur[maxN];
struct Eddge
{
    int nex, to, flow;
    Eddge(int a=-1, int b=0, int c=0):nex(a), to(b), flow(c) {}
}edge[maxN<<1];
inline void addEddge(int u, int v, int flow)
{
    edge[cnt] = Eddge(head[u], v, flow);
    head[u] = cnt++;
}
inline void _add(int u, int v, int flow) { addEddge(u, v, flow); addEddge(v, u, 0); }
int deep[maxN];
int Q[maxN<<1], top, tail;
bool bfs()
{
    for(int i=1; i<=N; i++) deep[i] = 0;
    deep[S] = 1;
    top = tail = 0;
    Q[++top] = S;
    while(tail < top)
    {
        int u = Q[++tail];
        if(u == T) break;
        for(int i=head[u], v, f; ~i; i=edge[i].nex)
        {
            v = edge[i].to; f = edge[i].flow;
            if(f > 0 && !deep[v])
            {
                deep[v] = deep[u] + 1;
                Q[++top] = v;
            }
        }
    }
    return deep[T];
}
int dfs(int u, int dist)
{
    if(u == T) return dist;
    for(int &i=cur[u], v, f; ~i; i=edge[i].nex)
    {
        v = edge[i].to; f = edge[i].flow;
        if(deep[v] == deep[u] + 1 && f > 0)
        {
            int di = dfs(v, min(dist, f));
            if(di)
            {
                edge[i].flow -= di;
                edge[i^1].flow += di;
                return di;
            }
        }
    }
    return 0;
}
int Dinic()
{
    int ans = 0, tmp;
    while(bfs())
    {
        for(int i=1; i<=N; i++) cur[i] = head[i];
        while((tmp = dfs(S, INF))) ans += tmp;
    }
    return ans;
}
inline void init()
{
    cnt = 0;
    for(int i=1; i<=N; i++) head[i] = -1;
}
int main()
{
    int Cas;  scanf("%d", &Cas);
    while(Cas--)
    {
        scanf("%d%d", &N, &M);
        init();
        int minn = INF, maxx = -INF;
        for(int i=1, x, y; i<=N; i++)
        {
            scanf("%d%d", &x, &y);
            if(x < minn)
            {
                minn = x;
                S = i;
            }
            if(x > maxx)
            {
                maxx = x;
                T = i;
            }
        }
        for(int i=1, u, v, w; i<=M; i++)
        {
            scanf("%d%d%d", &u, &v, &w);
            //_add(u, v, w);
            //_add(v, u, w);
            addEddge(u, v, w);
            addEddge(v, u, w);
        }
        printf("%d
", Dinic());
    }
    return 0;
}