hdu - 3549 Flow Problem (最大流模板题)

http://acm.hdu.edu.cn/showproblem.php?pid=3549

Ford-Fulkerson算法.

#include <iostream>
#include <cstdio>
#include <cmath>
#include <vector>
#include <cstring>
#include <string>
#include <algorithm>
#include <string>
#include <set>
#include <functional>
#include <numeric>
#include <sstream>
#include <stack>
#include <map>
#include <queue>
#pragma comment(linker, "/STACK:102400000,102400000")
#define CL(arr, val)    memset(arr, val, sizeof(arr))

#define ll long long
#define inf 0x7f7f7f7f
#define lc l,m,rt<<1
#define rc m + 1,r,rt<<1|1
#define pi acos(-1.0)

#define L(x)    (x) << 1
#define R(x)    (x) << 1 | 1
#define MID(l, r)   (l + r) >> 1
#define Min(x, y)   (x) < (y) ? (x) : (y)
#define Max(x, y)   (x) < (y) ? (y) : (x)
#define E(x)        (1 << (x))
#define iabs(x)     (x) < 0 ? -(x) : (x)
#define OUT(x)  printf("%I64d\n", x)
#define lowbit(x)   (x)&(-x)
#define Read()  freopen("a.txt", "r", stdin)
#define Write() freopen("b.txt", "w", stdout);
#define maxn 1010
#define maxv 1010
#define mod 1000000000
using namespace std;

struct edge
{
    int to,cap,rev;
    edge(){}
    edge(int x,int y,int z)
    {
        to=x;
        cap=y;
        rev=z;
    }
};

vector<edge>G[maxv];
bool used[maxv];

void add_edge(int from,int to,int cap)
{
    G[from].push_back((edge){to,cap,G[to].size()});
    G[to].push_back((edge){from,,G[from].size()-});
}

int dfs(int v,int t,int f)
{
    if(v==t) return f;
    used[v]=true;
    for(int i=;i<G[v].size();i++)
    {
        edge &e=G[v][i];
        if(!used[e.to]&&e.cap>)
        {
            int d=dfs(e.to,t,min(f,e.cap));
            if(d>)
            {
                e.cap-=d;
                G[e.to][e.rev].cap+=d;
             //   printf("%d %d\n",e.to,e.rev);
                return d;
            }
        }
    }
    return ;
}

int max_flow(int s,int t)
{
    int flow=;
    for(;;)
    {
        memset(used,,sizeof(used));
        int f=dfs(s,t,inf);
        if(f==) return flow;
        flow+=f;
    }
}
int main()
{
    //freopen("a.txt","r",stdin);
    int t,n,m,a,b,c,j=;
    scanf("%d",&t);
    while(t--)
    {
        scanf("%d%d",&n,&m);
        for(int i=;i<=n;i++)
            G[i].clear();
        for(int i=;i<m;i++)
        {
            scanf("%d%d%d",&a,&b,&c);
            add_edge(a,b,c);
        }
        printf("Case %d: %d\n",j++,max_flow(,n));
    }
    return ;
}

Dinic算法：(动态邻接表)

 #include <iostream>
 #include <cstdio>
 #include <cmath>
 #include <vector>
 #include <cstring>
 #include <string>
 #include <algorithm>
 #include <string>
 #include <set>
 #include <functional>
 #include <numeric>
 #include <sstream>
 #include <stack>
 #include <map>
 #include <queue>
 #pragma comment(linker, "/STACK:102400000,102400000")
 #define CL(arr, val)    memset(arr, val, sizeof(arr))

 #define ll long long
 #define inf 0x7f7f7f7f
 #define lc l,m,rt<<1
 #define rc m + 1,r,rt<<1|1
 #define pi acos(-1.0)

 #define L(x)    (x) << 1
 #define R(x)    (x) << 1 | 1
 #define MID(l, r)   (l + r) >> 1
 #define Min(x, y)   (x) < (y) ? (x) : (y)
 #define Max(x, y)   (x) < (y) ? (y) : (x)
 #define E(x)        (1 << (x))
 #define iabs(x)     (x) < 0 ? -(x) : (x)
 #define OUT(x)  printf("%I64d\n", x)
 #define lowbit(x)   (x)&(-x)
 #define Read()  freopen("a.txt", "r", stdin)
 #define Write() freopen("b.txt", "w", stdout);
 #define maxn 1010
 #define maxv 1010
 #define mod 1000000000
 using namespace std;

 struct edge
 {
     int to,cap,rev;
     edge(){}
     edge(int x,int y,int z)
     {
         to=x;
         cap=y;
         rev=z;
     }
 };

 vector<edge>G[maxv];
 int level[maxv];
 int iter[maxv];

 void add_edge(int from,int to,int cap)
 {
     G[from].push_back((edge){to,cap,G[to].size()});
     G[to].push_back((edge){from,,G[from].size()-});
 }

 void bfs(int s)
 {
     memset(level,-,sizeof(level));
     queue<int>que;
     level[s]=;
     que.push(s);
     while(!que.empty())
     {
         int v=que.front();que.pop();
         for(int i=;i<G[v].size();i++)
         {
             edge &e=G[v][i];
             if(e.cap>&&level[e.to]<)
             {
                 level[e.to]=level[v]+;
                 que.push(e.to);
             }
         }
     }
 }
 int dfs(int v,int t,int f)
 {
     if(v==t) return f;
     for(int &i=iter[v];i<G[v].size();i++)
     {
         edge &e=G[v][i];
         if(e.cap>&&level[v]<level[e.to])
         {
             int d=dfs(e.to,t,min(f,e.cap));
             if(d>)
             {
                 e.cap-=d;
                 G[e.to][e.rev].cap+=d;
               //  printf("%d %d %d\n",e.to,e.rev,G[e.to][e.rev]);
                 return d;
             }
         }
     }
     return ;
 }

 int max_flow(int s,int t)
 {
     int flow=;
     for(;;)
     {
         bfs(s);
         if(level[t]<) return flow;
         memset(iter,,sizeof(iter));
         int f;
         while((f=dfs(s,t,inf))>)
         flow+=f;
     }
 }
 int main()
 {
     //freopen("a.txt","r",stdin);
     int t,n,m,a,b,c,j=;
     scanf("%d",&t);
     while(t--)
     {
         scanf("%d%d",&n,&m);
         for(int i=;i<=n;i++)
             G[i].clear();
         for(int i=;i<m;i++)
         {
             scanf("%d%d%d",&a,&b,&c);
             add_edge(a,b,c);
         }
         printf("Case %d: %d\n",j++,max_flow(,n));
     }
     return ;
 }