UVA10735 混合图欧拉回路

from CAH，here
讲的比lrj还要详细，

个人的傻逼错误：
需要注意的是，网络流里是有反向边的，dinic跑完之后反向边不要添加到新图里面了

#include<queue>
#include<stack>
#include<cstdio>
#include<vector>
#include<string>
#include<cstring>
#include<iostream>
using namespace std;
typedef long long LL;
const int INF=0x3f3f3f3f;
const int N = 9999;

struct Euler
{
    struct Edge{
        int to,nxt;
        Edge(){}
        Edge(int x,int y):to(x),nxt(y){}
    }edges[N];
    int head[N],n,E;
    inline void Init(const int &n){
        this->n = n; E = 0;
        for (int i=0;i<=n;i++)head[i]=-1;
    }
    inline void AddEdge(int f,int t){
        edges[++E] = Edge(t,head[f]);
        head[f] = E ;
    }
    stack<int >S;
    bool vis[N];//use when dfs
    inline void dfs(int x){//get EulerCircle
        Edge e;
        for (int i=head[x];i!=-1;i=e.nxt){
            e = edges[i];
            if (vis[i])continue;
            vis[i] = 1;
            dfs(e.to);
            S.push(x);
        }
    }
    inline void getEulerCircle(){
        while (!S.empty())S.pop();
        memset(vis,0,sizeof(vis));
        dfs(1);
        for (;!S.empty();S.pop()){
            printf("%d ",S.top());
        }
        puts("1");
    }
}gg;

struct Dinic
{
    struct Edge{
        int from,to,cap,flow;
        Edge(int u,int v,int c,int f):
            from(u),to(v),cap(c),flow(f){}
    };
    int n, s, t;
    vector<Edge>edges;
    vector< int>G[N]; //gragh
    bool vis[N]; //use when bfs
    int d[N],cur[N];//dist,now edge,use in dfs
    inline 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 top = edges.size()  ;
        G[from].push_back(top-2);
        G[ to ].push_back(top-1);
    }
    inline void Init(int n,int s,int t){
        this -> n = n ;
        this -> s = s ;
        this -> t = t ;
        edges.clear();
        for (int i=0;i<=n;i++)G[i].clear();
    }

    inline bool BFS(){
        memset(vis,0,sizeof(vis));
        queue<int>Q;
        Q.push(s);d[s]=0;vis[s]=1;
        while (!Q.empty()){
            int x=Q.front();Q.pop();
            for (int i=0;i<G[x].size();i++){
                Edge &e=edges[G[x][i]];
                if (vis[e.to]||e.cap<=e.flow)continue;
                vis[e.to]=1;
                d[e.to]=d[x]+1;
                Q.push(e.to);
            }
        }
        return vis[t];
    }
    inline int DFS(const int& x,int a){
        if (x==t||a==0){return a;}
        int flow = 0, f;
        for (int& i=cur[x];i<G[x].size();i++){
            Edge& e=edges[G[x][i]];
            if (d[x]+1!=d[e.to])continue;
            if ((f=DFS(e.to,min(a,e.cap-e.flow)))<=0)continue;
            e.flow += f;
            edges[G[x][i]^1].flow-=f;//ϲߍ
            flow+=f; a-=f;
            if (!a) break;
        }
        return flow;
    }
    inline int maxFlow(){return maxFlow(s,t);}
    inline int maxFlow(int s, int t){
        int flow = 0;
        for (;BFS();){
            memset(cur,0,sizeof(cur));
            flow += DFS(s,INF) ;
        }
        return flow;
    }
    inline void buildEuler(int n){
        for (int i=1;i<=n;i++){
            for (int j=0;j<G[i].size();j++){
                Edge &e = edges[G[i][j]];
                if (e.to==s||e.to==t) continue ;
                if (!e.cap)continue;
                if (e.flow==e.cap)gg.AddEdge(e.to,e.from);
                else gg.AddEdge(e.from, e.to);
            }
        }
    }
} g ;

int d[N];//degree = out - in
bool work(int n){
    int flow = 0;
    for (int i=1;i<=n;i++){
        if (d[1]&1)return 0;
        if (d[i]>0){
            g.AddEdge(g.s,i,d[i]>>1);
            flow += d[i]>>1;
        }else if (d[i]<0)
            g.AddEdge(i,g.t,-(d[i]>>1));
    }
    if (flow != g.maxFlow()) return 0;
    return 1;
}

int main(){
    //freopen("in.txt","r",stdin);
    int T,x,y,n,m;
    scanf("%d",&T);
    for (char ch;T--;){
        scanf("%d%d",&n,&m);
        g.Init(n,0,n+1);
        gg.Init(n);
        memset(d,0,sizeof(d));
        for (int i=1;i<=m;i++){
            scanf("%d%d %c
",&x,&y,&ch);
            if (ch=='D') gg.AddEdge(x,y);
            else g.AddEdge(x,y,1);
            d[x]++;d[y]--;//Degree
        }
        if (!work(n))puts("No euler circuit exist");
        else {
            g.buildEuler(n);
            gg.getEulerCircle();
        }
        if (T)puts("");
    }
    return 0;
}

前行星的dinic板

struct Dinic
{
    struct Edge{
        int from,to,cap,flow,nxt;
        Edge(){}
        Edge(int u,int v,int c,int f,int n):
            from(u),to(v),cap(c),flow(f),nxt(n){}
    }edges[N];
    int n, s, t, E, head[N];
    bool vis[N]; //use when bfs
    int d[N],cur[N];//dist,now edge,use in dfs
    inline void AddEdge(int f,int t,int c){
        edges[++E] = Edge(f,t,c,0,head[f]);
        head[f] = E;
        edges[++E] = Edge(t,f,0,0,head[t]);
        head[t] = E;
    }
    inline void Init(int n,int s,int t){
        this -> n = n ; E = -1;
        this -> s = s ; head[s] = -1;
        this -> t = t ; head[t] = -1;
        for (int i=0;i<=n;i++) head[i] = -1;
    }

    inline bool BFS(){
        memset(vis,0,sizeof(vis));
        queue<int >Q;
        d[s] = 0; vis[s] = 1;
        for (Q.push(s);!Q.empty();){
            int x = Q.front(); Q.pop();
            for (int nxt,i = head[x];i!=-1;i = nxt){
                Edge &e = edges[i]; nxt = e.nxt;
                if (vis[e.to]||e.cap<=e.flow)continue;
                vis[e.to]=1;
                d[e.to]=d[x]+1;
                Q.push(e.to);
            }
        }
        return vis[t];
    }
    inline int DFS(const int& x,int a){
        if (x==t||a==0){return a;}
        int flow = 0, f, nxt;
        for (int& i=cur[x];i!=-1;i=nxt){
            Edge& e = edges[i]; nxt = e.nxt;
            if (d[x]+1!=d[e.to])continue;
            if ((f=DFS(e.to,min(a,e.cap-e.flow)))<=0)continue;
            e.flow += f;
            edges[i^1].flow-=f;//反向边
            flow+=f; a-=f;
            if (!a) break;
        }
        return flow;
    }
    inline int maxFlow(){return maxFlow(s,t);}
    inline int maxFlow(int s, int t){
        int flow = 0;
        for (;BFS();){
            for (int i=0;i<=n;i++)cur[i]=head[i];
            flow += DFS(s,INF) ;
        }
        return flow;
    }
    inline void buildEuler(int n){
        for (int i=1;i<=n;i++){
            for (int nxt,j=head[i];j!=-1;j=nxt){
                Edge &e = edges[j]; nxt = e.nxt;
                if (e.to==s||e.to==t) continue ;
                if (!e.cap)continue;
                if (e.flow==e.cap)gg.AddEdge(e.to,e.from);
                else gg.AddEdge(e.from, e.to);
            }
        }
    }
} g ;