sgu212

来源：互联网发布：linux如何查看时间编辑：程序博客网时间：2024/05/21 11:28

HLPP算法：http://xingzheqiang.blog.163.com/blog/static/20561012520127464654159/

时间复杂度: O(n2∗m−−√) (并不会证明。。。)，楼教说对于这种分层图HLPP实际效率更优，不管你信不信，我反正是信了。

#include<cstdio>#include<cstdlib>#include<queue>#include<utility>#include<iostream>#include<algorithm>const int maxn = 1505, maxl = 1505, maxm = 3e5+5, Nya = -1;const int Ni[2] = {-1,1}, INF = 0x3f3f3f3f;struct Edge{    int v, cap, next;    Edge(){}    Edge(int v,int cap,int next):v(v),cap(cap),next(next){}};std::priority_queue<std::pair<int,int> > heap; int head[maxn], el;Edge edge[maxm<<1];int n, m, L, S, T;int h[maxl], e[maxn];bool hash[maxn];void NewEdge(int u,int v,int w){    edge[++el] = Edge(v,w,head[u]), head[u] = el;}int HLPP_MaxFlow(){    hash[S] = hash[T] = true;    for(int i = head[S], p; i ; i = edge[i].next)    {        e[p = edge[i].v] = edge[i].cap;        edge[i+Ni[i&1]].cap += edge[i].cap;        if(!hash[p])        {            heap.push(std::make_pair(h[p], p));            hash[p] = true;        }    }    while(!heap.empty())    {        int u = heap.top().second, min = INF;        heap.pop(), hash[u] = false;        for(int i = head[u], v; i && e[u]; i = edge[i].next)        {            if(h[u] == h[v = edge[i].v] + 1 && edge[i].cap)            {                int flow = std::min(edge[i].cap, e[u]);                e[u] -= flow, edge[i].cap -= flow;                 e[v] += flow, edge[i+Ni[i&1]].cap += flow;                if(!hash[v])                {                    heap.push(std::make_pair(h[v],v));                    hash[v] = true;                }            }            if(edge[i].cap) min = std::min(h[v], min);         }        if(e[u])        {            h[u] = min + 1;            heap.push(std::make_pair(h[u], u));            hash[u] = true;         }    }}int main(){#ifndef ONLINE_JUDGE    freopen("sgu212.in","r",stdin);    freopen("sgu212.out","w",stdout);#endif    std::cin >> n >> m >> L;    for(int i = 1; i <= n; i++)    {        scanf("%d",&h[i]);        if(h[i] == 1) S = i;        if(h[i] == L) T = i;        h[i] = L - h[i] + 1;    }    for(int i = 1, u, v, w; i <= m; i++)    {        scanf("%d%d%d",&u,&v,&w);        NewEdge(u, v, w), NewEdge(v, u, 0);    }    HLPP_MaxFlow();    for(int i = 1; i <= m; i++)        printf("%d\n",edge[i<<1].cap);#ifndef ONLINE_JUDGE    fclose(stdin);    fclose(stdout);#endif    return 0;}

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