POJ 1087 网络流 最大流

设置源点和汇点，每个需要使用的设备插座，连接源点到该插座的设备个数，连接会场提供插座到汇点，容量为个数，然后连接插座转换边，容量为无穷

注意转换插座可能是之前没出现过的

#include <set>#include <map>#include <cmath>#include <queue>#include <stack>#include <string>#include <cstdio>#include <cstring>#include <iostream>#include <algorithm>using namespace std;typedef  long long LL;const double PI = acos(-1.0);template <class T> inline  T MAX(T a, T b){if (a > b) return a;return b;}template <class T> inline  T MIN(T a, T b){if (a < b) return a;return b;}const int N = 444;const int M = 1111;const LL MOD = 1000000007LL;const int dir[4][2] = {1, 0, -1, 0, 0, -1, 0, 1};const int INF = 0x3f3f3f3f;struct arclist {    struct edge{int v, cap, next;} E[N + M << 1];    int head[N], cur;    inline void init()    {        memset(head, -1, sizeof(head)); cur = 0;    }    inline void add(int u, int v, int cap = 1) {        E[cur].v = v; E[cur].cap = cap;        E[cur].next = head[u]; head[u] = cur++;        E[cur].v = u; E[cur].cap = 0;        E[cur].next = head[v]; head[v] = cur++;    }    int SAP(int S, int T, int n)    {        int maxflow = 0, pre[N], dis[N] = {}, gap[N] = {};        int cur[N]; memcpy(cur, head, sizeof(cur));        gap[0] = n + 1; ++gap[dis[S] = 1];        for (int u = pre[S] = S; dis[S] <= n; ++gap[++dis[u]], u = pre[u])        {            for (bool flag = true; flag;)            {                flag = false;                for (int &p = cur[u]; ~p; p = E[p].next)                {                    if (!E[p].cap || dis[u] != dis[E[p].v] + 1) continue;                    flag = true; pre[E[p].v] = u; u = E[p].v;                    if (u == T)                    {                        int aug = INF;                        for (int i = S; i != T; i = E[cur[i]].v)                            if (aug > E[cur[i]].cap)                            {                                u = i; aug = E[cur[i]].cap;                            }                        for (int i = S; i != T; i = E[cur[i]].v)                        {                            E[cur[i]].cap -= aug;                            E[cur[i] ^ 1].cap += aug;                        }                        maxflow += aug;                    }                    break;                }            }            if (--gap[dis[u]] == 0) break;            dis[u] = n;            for (int p = head[u]; ~p; p = E[p].next)                if (E[p].cap && dis[u] > dis[E[p].v]) {dis[u] = dis[E[p].v]; cur[u] = p;}        }        return maxflow;    }}flow;int to[N], from[N], ct[N], ct1[N];int trans[N], trant[N];int main(){        string s;        char str[50];        int num, n, i, j, k, tot, cnt3, cnt1, cnt2;        memset(ct, 0, sizeof(ct));        scanf("%d", &n);        flow.init();        cnt1 = cnt2 = cnt3 = 0;        tot = 1;        memset(to, 0, sizeof(to));        memset(ct1, 0, sizeof(ct1));        map < string , int > index;        for (i = 0; i < n; ++i)        {            int temp;            scanf("%s", str);            s = str;            if (index[s]) temp = index[s];            else {index[s] = tot++; temp = tot - 1;}            ct1[temp]++;        }        scanf("%d", &n);        num = n;        for (i = 0; i < n; ++i)        {            int temp;            char buf[N];            scanf("%s%s", buf, str);            s = str;            if (index[s]) temp = index[s];            else {index[s] = tot++; temp = tot - 1;}            ct[temp]++;        }        scanf("%d", &n);        for (i = 0; i < n; ++i)        {            int tp1, tp2;            char buf[N];            string s1;            //buf = s1.c_str();            scanf("%s%s", buf, str);            s1 = buf; s = str;            if (index[s1]) tp1 = index[s1];            else {index[s1] = tot++; tp1 = tot - 1;}            if (index[s]) tp2 = index[s];            else {index[s] = tot++; tp2 = tot - 1;}            trans[cnt3] = tp1; trant[cnt3++] = tp2;        }        for (i = 0; i < tot; ++i)        {            flow.add(i, tot, ct1[i]);        }        for (i = 0; i < tot; ++i)        {            if (!ct[i]) continue;            flow.add(0, i, ct[i]);        }        for (i = 0; i < cnt3; ++i)            flow.add(trans[i], trant[i], INF);        printf("%d\n", num -  flow.SAP(0, tot, tot + 1));    return 0;}