POJ-1273（Dinic）题解 (漂亮版代码)

来源：互联网发布：圣火明尊盾牌进阶数据编辑：程序博客网时间：2024/05/16 15:14

信息课把代码变得漂亮了一些，然而想加上内存优化发现并不可以，FUKK。

#include "queue"#include "cstdio"#include "cstring"using namespace std;#define min(a, b) ((a) < (b) ? (a) : (b))const int MAXN = (int) 200 + 5, oo = 0x3f3f3f3f;int m, n, ne = 1, u, v, c, head[MAXN];struct edge  {    int to, cap, flow, pre;    inline bool adde  ( int to, int cap, int flow, int pre )  {        this->to = to, this->cap = cap, this->flow = flow, this->pre = pre;    }}g[MAXN << 1];inline bool adde( int from, int to, int cap )  {    g[++ne].adde( to, cap, 0, head[from] ); head[from] = ne;    g[++ne].adde( from, 0, 0, head[to] ); head[to] = ne;}class Dinic{private:    int d[MAXN], cur[MAXN], s, t;    bool vis[MAXN];    inline bool init()  {        memset(vis, false, sizeof(vis));        for( register int i = 1; i <= n; ++i )  cur[i] = head[i];    }public:    bool bfs(int s, int t)  {               queue<int> Q;        d[s] = 0, vis[s] = true;        Q.push(s);        while(!Q.empty())  {            int u = Q.front();  Q.pop();            for( int i = head[u]; i; i = g[i].pre )  {                int v = g[i].to;                if( !vis[v] && g[i].cap > g[i].flow )  {                    vis[v] = true;                    d[v] = d[u] + 1;                    Q.push(v);                }            }        }        return vis[t];    }    inline int dfs( int u, int a )  {        if( u == t || !a )  return a;        int flow = 0, f;        for(register int &i = cur[u]; i; i = g[i].pre )  {            int  v = g[i].to;            if( d[u] + 1 == d[v] && (f = dfs(v, min(g[i].cap - g[i].flow, a))) > 0)  {                g[i].flow += f;                g[i^1].flow -= f;                flow += f;                a -= f;                if(!a)  return flow;            }        }        return flow;    }    int Maxflow( int s, int t )  {        this -> s = s, this -> t = t;        int flow = 0;        while( bfs(s, t) )  {            init();            flow += dfs(s, oo);        }        return flow;    }} Dinic;int main()  {    while(scanf("%d%d", &n, &m) == 2)  {        ne = 1;        memset(head, 0, sizeof(head));        for(register int i = 1; i <= n; ++i )  scanf("%d%d%d", &u, &v, &c), adde(u, v, c);        printf("%d\n", Dinic.Maxflow(1, m));    }    return 0;}

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