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poj 3308 Paratroopers

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poj 3308 Paratroopers

#include <iostream>#include <cstdlib>#include <cstring>#include <cstdio>#include <cmath>using namespace std;#define inf 0x3f3f3f3f#define maxn 55#define maxl 505#define N maxn * 2#define E (N + maxl) * 2int n, m, num;int s, t;struct edge{    int x, y, nxt;    double c;}bf[E];int ne, head[N], cur[N], ps[N], dep[N];void addedge1(int x, int y, double c){    bf[ne].x = x;    bf[ne].y = y;    bf[ne].c = c;    bf[ne].nxt = head[x];    head[x] = ne++;}void addedge(int x, int y, double c){    addedge1(x, y, c);    addedge1(y, x, 0);}double flow(int n, int s, int t){    double 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(){    scanf("%d%d%d", &n, &m, &num);    s = 0;    t = n + m + 1;    for (int i = 1; i <= n; i++)    {        double a;        scanf("%lf", &a);        addedge(s, i, log(a));    }    for (int i = n + 1; i <= n + m; i++)    {        double a;        scanf("%lf", &a);        addedge(i, t, log(a));    }    for (int i = 0; i < num; i++)    {        int a, b;        scanf("%d%d", &a, &b);        addedge(a, n + b, inf);    }}int main(){    int case_num;    scanf("%d", &case_num);    while (case_num--)    {        ne = 2;        memset(head, 0, sizeof(head));        input();        printf("%.4fn", exp(flow(n + m + 2, s, t)));    }    return 0;}
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