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Purdue University
Computer Science, Math

Xiaonan Shen's avatar Xiaonan Shen

[BZOJ1433][ZJOI2009]假期的宿舍(最大流)

又是一道最大流,建图很简单,源点到所有的在校学生和外校学生建一条容量为1的边,所有在校学生的床(感觉听起来怪怪的)到汇点连一条边,所有在校学生和自己的床连一条边,所有学生到他认识的在校学生的床连一条边。然后做最大流与需要住校的学生总数比较,相等就输出^_^,不相等就输出T_T(这个太逗了)。。

//ZJOI2009 holiday.cpp
#include<algorithm>
#include<iostream>
#include<cstring>
#include<cstdlib>
#include<cstdio>
#include<vector>
#include<cmath>
#include<queue>
#include<stack>
#include<map>
#include<set>

//#define LOCAL
//#define READ_FILE
#define READ_FREAD
//#define VISUAL_STUDIO

const int MAXN = 50;
const int MAXPT = 110;

#ifdef LOCAL
#define LOCAL_TIME
#define LOCAL_DEBUG
//#define STD_DEBUG
#endif

#ifdef VISUAL_STUDIO
#pragma warning(disable: 4996)
#endif

#ifdef LOCAL_TIME
#include<ctime>
#endif

#ifdef READ_FREAD
char fread_char;

inline void fread_init()
{
    fread_char = getchar();
}

inline int get_int()
{
    int ret = 0;
    while ((fread_char < '0') || (fread_char > '9'))
    {
        fread_char = getchar();
    }
    while ((fread_char >= '0') && (fread_char <= '9'))
    {
        ret = ret * 10 + fread_char - '0';
        fread_char = getchar();
    }
    return ret;
}
#endif

inline void read(int &a)
{
#ifdef READ_FREAD
    a = get_int();
#else
    scanf("%d", &a);
#endif
}

struct queue_node
{
    int id, height;
    inline queue_node(const int id_ = 0, const int height_ = 0)
    {
        id = id_;
        height = height_;
    }
    inline bool operator < (const queue_node &b) const
    {
        return height < b.height;
    }
};

int cases, n;
int s, t;
int tot_at_school;
int school_student[MAXN];
int at_home[MAXN];
int k;
int graph[MAXPT][MAXPT];
int height[MAXPT], inflow[MAXPT], gap[MAXPT];
bool visit[MAXPT], in_q[MAXPT];
std::queue <int> bfs_q;
std::priority_queue <queue_node> Q;

inline void add_edge(const int u, const int v)
{
#ifdef LOCAL_DEBUG
    printf("ADDEDGE %d %dn", u, v);
#endif
    graph[u][v] = 1;
}

inline void bfs()
{
    memset(visit, false, sizeof(visit));
    memset(height, 0, sizeof(height));
    memset(gap, 0, sizeof(gap));
    gap[0] = 1;
    bfs_q.push(t);
    int tmp;
    while (!bfs_q.empty())
    {
        tmp = bfs_q.front();
        bfs_q.pop();
        for (int i = s; i < t; i++)
        {
            if ((graph[i][tmp] > 0) && (!visit[i]))
            {
                gap[height[i] = height[tmp] + 1]++;
                visit[i] = true;
                bfs_q.push(i);
            }
        }
    }
}

inline int max_flow()
{
    memset(in_q, false, sizeof(in_q));
    memset(inflow, 0, sizeof(inflow));
    in_q[s] = in_q[t] = true;
    for (int i = 1; i <= n; i++)
    {
        if (graph[s][i] > 0)
        {
            graph[i][s] = inflow[i] = graph[s][i];
            graph[s][i] = 0;
            in_q[i] = true;
            Q.push(queue_node(i, height[i]));
        }
    }
    queue_node tmp;
    int push_flow = -1;
    int min_height = -1;
    while (!Q.empty())
    {
        tmp = Q.top();
        Q.pop();
#ifdef LOCAL_DEBUG
        printf("POP ID HEIGHT INFLOW: %d %d %dn", tmp.id, tmp.height, inflow[tmp.id]);
#endif
        in_q[tmp.id] = false;
        for (int i = s + 1; (i <= t) && (inflow[tmp.id] > 0); i++)
        {
            if ((graph[tmp.id][i] > 0) && (height[tmp.id] == height[i] + 1))
            {
                push_flow = std::min(graph[tmp.id][i], inflow[tmp.id]);
                graph[tmp.id][i] -= push_flow;
                graph[i][tmp.id] += push_flow;
                inflow[tmp.id] -= push_flow;
                inflow[i] += push_flow;
                if (!in_q[i])
                {
                    in_q[i] = true;
                    Q.push(queue_node(i, height[i]));
                }
            }
        }
        if ((inflow[tmp.id] > 0) && (tmp.id < t))
        {
            min_height = -1;
            for (int i = s + 1; i <= t; i++)
            {
                if (graph[tmp.id][i] > 0)
                {
                    if ((min_height == -1) || (min_height > height[i]))
                    {
                        min_height = height[i];
                    }
                }
            }
            if ((min_height > -1) & (min_height < t))
            {
                gap[height[tmp.id]]--;
                if (gap[height[tmp.id]] == 0)
                {
                    for (int i = s + 1; i < t; i++)
                    {
                        if ((height[i] >= height[tmp.id]) && (height[i] < t))
                        {
                            gap[height[i]]--;
                            height[i] = t;
                            if (in_q[i])
                            {
                                Q.pop();
                            }
                            else
                            {
                                in_q[i] = true;
                            }
                        }
                    }
                }
                else
                {
                    gap[height[tmp.id] = min_height + 1]++;
                    in_q[tmp.id] = true;
                    Q.push(queue_node(tmp.id, height[tmp.id]));
                }
            }
        }
    }
    return inflow[t];
}

int main()
{
#ifdef LOCAL_TIME
    long long start_time_ = clock();
#endif
#ifdef READ_FILE
    freopen("holiday.in", "r", stdin);
#ifndef STD_DEBUG
    freopen("holiday.out", "w", stdout);
#endif
#endif
    read(cases);
    while (cases--)
    {
        read(n);
        s = 0;
        t = 2 * n + 1;
        tot_at_school = 0;
        memset(graph, 0, sizeof(graph));
        for (int i = 1; i <= n; i++)
        {
            read(school_student[i]);
            if (school_student[i])
            {
                add_edge(n + i, t);
            }
            else
            {
                add_edge(s, i);
                tot_at_school++;
            }
        }
        for (int i = 1; i <= n; i++)
        {
            read(at_home[i]);
            if (school_student[i] && (!at_home[i]))
            {
                add_edge(s, i);
                tot_at_school++;
            }
        }
        for (int i = 1; i <= n; i++)
        {
            for (int j = 1; j <= n; j++)
            {
                read(k);
                if (i == j)
                {
                    if (school_student[i])
                    {
                        add_edge(i, n + i);
                    }
                }
                else if (k)
                {
                    if (school_student[i])
                    {
                        add_edge(j, n + i);
                    }
                    if (school_student[j])
                    {
                        add_edge(i, n + j);
                    }
                }
            }
        }
        bfs();
#ifdef LOCAL_DEBUG
        int ret = max_flow();
        printf("%d %dn", ret, tot_at_school);
        if (ret == tot_at_school)
#else
        if (max_flow() == tot_at_school)
#endif
        {
            printf("^_^n");
        }
        else
        {
            printf("T_Tn");
        }
    }
#ifdef LOCAL_TIME
    printf("run time: %lld msn", clock() - start_time_);
#endif
#ifdef READ_FILE
    fclose(stdin);
#ifndef STD_DEBUG
    fclose(stdout);
#endif
#endif
    return 0;
}

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