一开始就知道是最小割模型，然后开始乱搞建图，发现自己想错了。。。
Orz PoPoQQQ，还给蒟蒻提供了很多帮助！
1 /************************************************************** 2 Problem: 2039 3 User: rausen 4 Language: C++ 5 Result: Accepted 6 Time:5984 ms 7 Memory:64264 kb 8 ****************************************************************/ 9 10 #include <cstdio> 11 #include <cstring> 12 #include <algorithm> 13 14 using namespace std; 15 typedef long long ll; 16 const int N = 1005; 17 const int M = 4 * N * (N + 5); 18 const ll inf = (ll) 1e60; 19 20 struct edge { 21 int next, to; 22 ll f; 23 edge() {} 24 edge(int _n, int _t, ll _f) : next(_n), to(_t), f(_f) {} 25 } e[M]; 26 27 int n, S, T; 28 int first[N], tot = 1; 29 ll ans, a[N]; 30 int q[N], d[N]; 31 32 int read() { 33 int x = 0; 34 char ch = getchar(); 35 while (ch < '0' || '9' < ch) 36 ch = getchar(); 37 while ('0' <= ch && ch <= '9') 38 (x *= 10) += ch - '0', ch = getchar(); 39 return x; 40 } 41 42 inline void add_edges(int x, int y, ll z) { 43 e[++tot] = edge(first[x], y, z), first[x] = tot; 44 e[++tot] = edge(first[y], x, 0), first[y] = tot; 45 } 46 47 inline void Add_Edges(int x, int y, int z) { 48 add_edges(x, y, z); 49 add_edges(y, x, z); 50 } 51 52 #define y e[x].to 53 #define p q[l] 54 bool bfs() { 55 int l, r, x; 56 memset(d, -1, sizeof(d)); 57 d[q[1] = S] = 1; 58 for (l = r = 1; l != r + 1; ++l) 59 for (x = first[p]; x; x = e[x].next) 60 if (!~d[y] && e[x].f) { 61 d[q[++r] = y] = d[p] + 1; 62 if (y == T) return 1; 63 } 64 return 0; 65 } 66 #undef p 67 68 ll dfs(int p, ll lim) { 69 if (p == T || !lim) return lim; 70 int x; 71 ll tmp, rest = lim; 72 for (x = first[p]; x && rest; x = e[x].next) 73 if (d[y] == d[p] + 1 && ((tmp = min(e[x].f, rest)) > 0)) { 74 rest -= (tmp = dfs(y, tmp)); 75 e[x].f -= tmp, e[x ^ 1].f += tmp; 76 if (!rest) return lim; 77 } 78 if (rest) d[p] = -1; 79 return lim - rest; 80 } 81 #undef y 82 83 ll Dinic() { 84 ll res = 0; 85 while (bfs()) 86 res += dfs(S, inf); 87 return res; 88 } 89 90 int main() { 91 int i, j, E; 92 n = read(); 93 S = n + 1, T = n + 2; 94 for (i = 1; i <= n; ++i) 95 add_edges(i, T, read()); 96 for (i = 1; i <= n; ++i) 97 for (j = 1; j <= n; ++j) { 98 ans += (E = read()); 99 if (i < j) { 100 a[i] += E, a[j] += E; 101 Add_Edges(i, j, (ll) E << 1); 102 } 103 } 104 for (i = 1; i <= n; ++i) 105 add_edges(S, i, a[i]); 106 printf("%lld ", ans - Dinic()); 107 return 0; 108 }
(p.s. 新的最大流模板get！)