二分答案。。。然后最大流验证是否可行。。。
没了，好水啊QAQ
1 /************************************************************** 2 Problem: 3993 3 User: rausen 4 Language: C++ 5 Result: Accepted 6 Time:40 ms 7 Memory:1156 kb 8 ****************************************************************/ 9 10 #include <cstdio> 11 #include <cstring> 12 #include <algorithm> 13 14 using namespace std; 15 typedef double lf; 16 const int N = 105; 17 const lf inf = 1e10; 18 const lf eps = 1e-7; 19 const int M = N * N << 1; 20 21 inline int read(); 22 23 struct edge { 24 int next, to; 25 lf f; 26 edge(int _n = 0, int _t = 0, lf _f = 0.0) : next(_n), to(_t), f(_f) {} 27 } e[M]; 28 29 int n, m, S, T; 30 int b[N]; 31 int first[N], tot = 1; 32 int q[N], d[N]; 33 34 inline void Add_Edges(int x, int y, lf z) { 35 e[++tot] = edge(first[x], y, z), first[x] = tot; 36 e[++tot] = edge(first[y], x, 0), first[y] = tot; 37 } 38 39 #define y e[x].to 40 #define p q[l] 41 bool bfs() { 42 static int l, r, x; 43 memset(d, -1, sizeof(d)); 44 d[q[1] = S] = 1; 45 for (l = r = 1; l != r + 1; ++l) 46 for (x = first[p]; x; x = e[x].next) 47 if (!~d[y] && e[x].f > eps) { 48 d[q[++r] = y] = d[p] + 1; 49 if (y == T) return 1; 50 } 51 return 0; 52 } 53 #undef p 54 55 lf dfs(int p, lf lim) { 56 if (p == T || !lim) return lim; 57 int x; 58 lf tmp, rest = lim; 59 for (x = first[p]; x && rest > eps; x = e[x].next) 60 if (d[y] == d[p] + 1 && ((tmp = min(e[x].f, rest)) > eps)) { 61 rest -= (tmp = dfs(y, tmp)); 62 e[x].f -= tmp, e[x ^ 1].f += tmp; 63 if (!rest) return lim; 64 } 65 if (rest > eps) d[p] = -1; 66 return lim - rest; 67 } 68 69 inline bool check(lf t) { 70 static int x; 71 for (x = 2; x <= tot; x += 2) 72 e[x].f += e[x ^ 1].f, e[x ^ 1].f = 0; 73 for (x = first[S]; x; x = e[x].next) 74 e[x].f = b[y - n] * t; 75 while (bfs()) dfs(S, inf); 76 for (x = first[T]; x; x = e[x].next) 77 if (e[x ^ 1].f > eps) return 0; 78 return 1; 79 } 80 #undef y 81 82 int main() { 83 int i, j; 84 lf l, r, mid; 85 n = read(), m = read(); 86 S = n + m + 1, T = S + 1; 87 for (i = 1; i <= n; ++i) 88 Add_Edges(i, T, read()); 89 for (i = 1; i <= m; ++i) 90 b[i] = read(), Add_Edges(S, n + i, 0); 91 for (i = 1; i <= m; ++i) 92 for (j = 1; j <= n; ++j) 93 if (read() == 1) Add_Edges(n + i, j, inf); 94 l = 0, r = 5e6; 95 while (r - l > eps) { 96 mid = (l + r) / 2.0; 97 if (check(mid)) r = mid; 98 else l = mid; 99 } 100 printf("%.6lf ", (l + r) / 2.0); 101 return 0; 102 } 103 104 inline int read() { 105 static int x; 106 static char ch; 107 x = 0, ch = getchar(); 108 while (ch < '0' || '9' < ch) 109 ch = getchar(); 110 while ('0' <= ch && ch <= '9') { 111 x = x * 10 + ch - '0'; 112 ch = getchar(); 113 } 114 return x; 115 } 116