poj1087

最大流

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#include <iostream>
#include <cstdio>
#include <cstdlib>
#include <cstring>
using namespace std;

#define N 505
#define E 1005
#define inf 0x3f3f3f3f
#define maxl 35

struct edge
{
    int x, y, nxt;
    int c;
} bf[E];

int ne, head[N], cur[N], ps[N], dep[N];
char name1[N][maxl], name2[N][maxl];
int s, t;
int n, m, k;

int getid(int &n, char name[][maxl], char *st)
{
    for (int i = 0; i < n; i++)
        if (strcmp(st, name[i]) == 0)
            return i;
    strcpy(name[n++], st);
    return n - 1;
}

void addedge(int x,int y, int c)
{
    bf[ne].x = x;
    bf[ne].y = y;
    bf[ne].c = c;
    bf[ne].nxt = head[x];
    head[x] = ne++;
    bf[ne].x = y;
    bf[ne].y = x;
    bf[ne].c = 0;
    bf[ne].nxt = head[y];
    head[y] = ne++;
}

int flow(int n, int s,  int t)
{
    int tr, res = 0;

    int i, j, k, f, r, top;
    while (1)
    {
        memset(dep, -1, n * sizeof(int));
        for (f = dep[ps[0] = s] = 0, r = 1; f != r;)
            for (i = ps[f++], j = head[i]; j; j = bf[j].nxt)
            {
                if (bf[j].c && -1 == dep[k = bf[j].y])
                {
                    dep[k] = dep[i] + 1; ps[r++] = k;
                    if (k == t)
                    {
                        f = r;
                        break;
                    }
                }
            }
        if (-1 == dep[t])
            break;

        memcpy(cur, head, n * sizeof(int));
        for (i = s, top = 0;;)
        {
            if (i == t)
            {
                for (k = 0, tr = inf; k < top; ++k)
                    if (bf[ps[k]].c < tr)
                        tr = bf[ps[f = k]].c;
                for (k = 0; k < top; ++k)
                    bf[ps[k]].c -= tr, bf[ps[k]^1].c += tr;
                res += tr;
                i = bf[ps[top = f]].x;
            }
            for (j = cur[i]; cur[i]; j = cur[i] = bf[cur[i]].nxt)
                if (bf[j].c && dep[i] + 1 == dep[bf[j].y])
                    break;
            if (cur[i])
            {
                ps[top++] = cur[i];
                i = bf[cur[i]].y;
            }
            else
            {
                if (0 == top)
                    break;
                dep[i] = -1; i = bf[ps[--top]].x;
            }
        }
    }
    return res;
}

void input()
{
    char st[maxl];
    char st1[maxl];
    int x;

    scanf("%d", &n);
    s = 0;
    t = 1;
    x = n;
    for (int i = 0; i < n; i++)
        scanf("%s", name1[i]);
    scanf("%d", &m);
    for (int i = 0; i < m; i++)
    {
        scanf("%s%s", name2[i], st);
        addedge(i + 2, m + getid(n, name1, st) + 2, 1);
        addedge(s, i + 2, 1);
    }
    scanf("%d", &k);
    for (int i = 0; i < k; i++)
    {
        scanf("%s%s", st1, st);
        addedge(getid(n, name1, st1) + m + 2, getid(n, name1, st) + m + 2, inf);
    }
    for (int i = 0; i < x; i++)
        addedge(i + m + 2, t, 1);
}

int main()
{
    //freopen("t.txt", "r", stdin);
    ne = 2;
    memset(head, 0, sizeof(head));
    input();
    printf("%d\n", m - flow(n + m + 2, s, t));
    return 0;
}