Crazy Circuits HDU - 3157（有源汇有上下界最小流）

时间：2022-10-20 18:19:47

给出每条边的下界 求最小流

板题

提供两个板子代码 虽然这个题 第一个比较快

但在loj上https://loj.ac/problem/117

的板题  第一个1700+ms

第二个才600+ms  用输入挂后400+ms

#include <iostream>

#include <cstdio>

#include <sstream>

#include <cstring>

#include <map>

#include <cctype>

#include <set>

#include <vector>

#include <stack>

#include <queue>

#include <algorithm>

#include <cmath>

#include <bitset>

#define rap(i, a, n) for(int i=a; i<=n; i++)

#define rep(i, a, n) for(int i=a; i<n; i++)

#define lap(i, a, n) for(int i=n; i>=a; i--)

#define lep(i, a, n) for(int i=n; i>a; i--)

#define rd(a) scanf("%d", &a)

#define rlld(a) scanf("%lld", &a)

#define rc(a) scanf("%c", &a)

#define rs(a) scanf("%s", a)

#define rb(a) scanf("%lf", &a)

#define rf(a) scanf("%f", &a)

#define pd(a) printf("%d\n", a)

#define plld(a) printf("%lld\n", a)

#define pc(a) printf("%c\n", a)

#define ps(a) printf("%s\n", a)

#define MOD 2018

#define LL long long

#define ULL unsigned long long

#define Pair pair<int, int>

#define mem(a, b) memset(a, b, sizeof(a))

#define _  ios_base::sync_with_stdio(0),cin.tie(0)

//freopen("1.txt", "r", stdin);

using namespace std;

const int maxn = 1e5 + , INF = 0x7fffffff;

int n, m, s, t;

int head[maxn], cur[maxn], vis[maxn], nex[maxn << ], in[maxn];

int d[maxn];

int cnt;

struct node

{

    int u, v;

    int c;

}Node[maxn << ];

void add_(int u, int v, int c)

{

    Node[cnt].u = u;

    Node[cnt].v = v;

    Node[cnt].c = c;

    nex[cnt] = head[u];

    head[u] = cnt++;

}

void add(int u, int v, int c)

{

    add_(u, v, c);

    add_(v, u, );

}

bool bfs()

{

    queue<int> Q;

    mem(d, );

    Q.push(s);

    d[s] = ;

    while(!Q.empty())

    {

        int u = Q.front(); Q.pop();

        for(int i = head[u]; i != -; i = nex[i])

        {

            int v = Node[i].v;

            if(!d[v] && Node[i].c > )

            {

                d[v] = d[u] + ;

                Q.push(v);

                if(v == t) return ;

            }

        }

    }

    return d[t] != ;

}

int dfs(int u, int cap)

{

    int ret = ;

    if(u == t || cap == )

        return cap;

    for(int &i = cur[u]; i != -; i = nex[i])

    {

        int v = Node[i].v;

        if(d[v] == d[u] +  && Node[i].c > )

        {

            int V = dfs(v, min(cap, Node[i].c));

            Node[i].c -= V;

            Node[i ^ ].c += V;

            ret += V;

            cap -= V;

            if(cap == ) break;

        }

    }

    if(cap > ) d[u] = -;

    return ret;

}

int Dinic()

{

    int ans = ;

    while(bfs())

    {

        memcpy(cur, head, sizeof head);

        ans += dfs(s, INF);

    }

    return ans;

}

int tranf(string x)

{

    if(x == "+") return ;

    if(x == "-") return n + ;

    int ans = , len = x.size();

    for(int i = ; i < len; i++)

    {

        ans += (x[i] - '') * pow(, len - i - );

    }

    return ans + ;

}

int main()

{

    int w;

    string u, v;

    int u_, v_;

    while(~scanf("%d%d", &n, &m))

    {

        if(n ==  && m == ) break;

        mem(head, -);

        cnt = ;

        mem(in, );

        int sum = ;

        s = , t = n + ;

        rap(i, , m)

        {

            // scanf(" %c %c %d", &u, &v, &w);

            cin >> u >> v >> w;

            u_ = tranf(u);

            v_ = tranf(v);

            add(u_, v_, INF - w);

            in[v_] += w;

            in[u_] -= w;

        }

        for(int i = ; i <= n + ; i++)

        {

            if(in[i] > )

            {

                sum += in[i];

                add(s, i, in[i]);

            }

            else

                add(i, t, -in[i]);

        }

        int ans = Dinic();

        add(n + , , INF);

        ans += Dinic();

        if(sum == ans)

            cout << Node[head[(n + )] ^ ].c << endl;

        else

            cout << "impossible" << endl;

    }

    return ;

}
#include <iostream>

#include <cstdio>

#include <sstream>

#include <cstring>

#include <map>

#include <cctype>

#include <set>

#include <vector>

#include <stack>

#include <queue>

#include <algorithm>

#include <cmath>

#include <bitset>

#define rap(i, a, n) for(int i=a; i<=n; i++)

#define rep(i, a, n) for(int i=a; i<n; i++)

#define lap(i, a, n) for(int i=n; i>=a; i--)

#define lep(i, a, n) for(int i=n; i>a; i--)

#define rd(a) scanf("%d", &a)

#define rlld(a) scanf("%lld", &a)

#define rc(a) scanf("%c", &a)

#define rs(a) scanf("%s", a)

#define rb(a) scanf("%lf", &a)

#define rf(a) scanf("%f", &a)

#define pd(a) printf("%d\n", a)

#define plld(a) printf("%lld\n", a)

#define pc(a) printf("%c\n", a)

#define ps(a) printf("%s\n", a)

#define MOD 2018

#define LL long long

#define ULL unsigned long long

#define Pair pair<int, int>

#define mem(a, b) memset(a, b, sizeof(a))

#define _  ios_base::sync_with_stdio(0),cin.tie(0)

//freopen("1.txt", "r", stdin);

using namespace std;

const int maxn = 1e5 + , INF = 0x7fffffff;

int n, m, s, t;

int head[maxn], cur[maxn], vis[maxn], nex[maxn << ], in[maxn];

int d[maxn];

int cnt;

struct node

{

    int u, v, bz;

    int c;

}Node[maxn << ];

void add_(int u, int v, int c, int bz)

{

    Node[cnt].u = u;

    Node[cnt].v = v;

    Node[cnt].c = c;

    Node[cnt].bz = bz;

    nex[cnt] = head[u];

    head[u] = cnt++;

}

void add(int u, int v, int c, int bz)

{

    add_(u, v, c, bz);

    add_(v, u, , bz);

}

bool bfs()

{

    queue<int> Q;

    mem(d, );

    Q.push(s);

    d[s] = ;

    while(!Q.empty())

    {

        int u = Q.front(); Q.pop();

        for(int i = head[u]; i != -; i = nex[i])

        {

            int v = Node[i].v;

            if(!d[v] && Node[i].c > )

            {

                d[v] = d[u] + ;

                Q.push(v);

                if(v == t) return ;

            }

        }

    }

    return d[t] != ;

}

int dfs(int u, int cap)

{

    int ret = ;

    if(u == t || cap == )

        return cap;

    for(int &i = cur[u]; i != -; i = nex[i])

    {

        int v = Node[i].v;

        if(d[v] == d[u] +  && Node[i].c > )

        {

            int V = dfs(v, min(cap, Node[i].c));

            Node[i].c -= V;

            Node[i ^ ].c += V;

            ret += V;

            cap -= V;

            if(cap == ) break;

        }

    }

    if(cap > ) d[u] = -;

    return ret;

}

int Dinic()

{

    int ans = ;

    while(bfs())

    {

        memcpy(cur, head, sizeof head);

        ans += dfs(s, INF);

    }

    return ans;

}

int tranf(string x)

{

    if(x == "+") return ;

    if(x == "-") return n + ;

    int ans = , len = x.size();

    for(int i = ; i < len; i++)

    {

        ans += (x[i] - '') * pow(, len - i - );

    }

    return ans + ;

}

int main()

{

    int w;

    string u, v;

    int u_, v_;

    while(~scanf("%d%d", &n, &m))

    {

        if(n ==  && m == ) break;

        mem(head, -);

        cnt = ;

        mem(in, );

        int sum = ;

        s = , t = n + ;

        rap(i, , m)

        {

            // scanf(" %c %c %d", &u, &v, &w);

            cin >> u >> v >> w;

            u_ = tranf(u);

            v_ = tranf(v);

            add(u_, v_, INF - w, );

            in[v_] += w;

            in[u_] -= w;

        }

        for(int i = ; i <= n + ; i++)

        {

            if(in[i] > )

            {

                sum += in[i];

                add(s, i, in[i], );

            }

            else

                add(i, t, -in[i], );

        }

        add(n + , , INF, );

        if(sum != Dinic())

            ps("impossible");

        else

        {

            sum = Node[head[n + ] ^ ].c;

            for(int i = ; i < cnt; i++)

            {

                if(!Node[i].bz) Node[i].v = ;

            }

            head[s] = head[t] = -;

            s = n + ;

            t = ;

            cout << sum - Dinic() << endl;

        }

    }

    return ;

}

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