题目传送门
1 /*
2 KM： 相比HDOJ_1533，多了重边的处理，还有完美匹配的判定方法
3 */
4 #include <cstdio>
5 #include <cmath>
6 #include <algorithm>
7 #include <cstring>
8 using namespace std;
9
10 const int MAXN = 1e2 + 10;
11 const int INF = 0x3f3f3f3f;
12 int x[MAXN], y[MAXN];
13 int w[MAXN][MAXN];
14 int visx[MAXN], visy[MAXN];
15 int ly[MAXN];
16 int n, m, d;
17
18 bool DFS(int u) {
19 visx[u] = true;
20 for (int i=1; i<=n; ++i) {
21 if (!visy[i] && x[u] + y[i] == w[u][i]) {
22 visy[i] = true;
23 if (ly[i] == -1 || DFS (ly[i])) {
24 ly[i] = u; return true;
25 }
26 }
27 else if (x[u] + y[i] > w[u][i]) d = min (d, x[u] + y[i] - w[u][i]);
28 }
29 return false;
30 }
31
32 int KM(void) {
33 for (int i=1; i<=n; ++i) {
34 x[i] = -INF;
35 for (int j=1; j<=n; ++j) {
36 x[i] = max (x[i], w[i][j]);
37 }
38 }
39
40 memset (ly, -1, sizeof (ly));
41 memset (y, 0, sizeof (y));
42 for (int i=1; i<=n; ++i) {
43 while (true) {
44 memset (visx, false, sizeof (visx));
45 memset (visy, false, sizeof (visy));
46 d = INF;
47 if (DFS (i)) break;
48 for (int i=1; i<=n; ++i) {
49 if (visx[i]) x[i] -= d;
50 }
51 for (int j=1; j<=n; ++j) {
52 if (visy[j]) y[j] += d;
53 }
54 }
55 }
56
57 for (int i=1; i<=n; ++i) {
58 if (ly[i] == -1 || w[ly[i]][i] == -INF) return -1;
59 }
60
61 int res = 0;
62 for (int i=1; i<=n; ++i) {
63 res += x[i] + y[i];
64 }
65
66 return -res;
67 }
68
69 int main(void) { //HDOJ 1853 Cyclic Tour
70 //freopen ("HDOJ_1853.in", "r", stdin);
71
72 while (scanf ("%d%d", &n, &m) == 2) {
73 if (!n && !m) break;
74 for (int i=1; i<=n; ++i) {
75 for (int j=1; j<=n; ++j) w[i][j] = -INF;
76 }
77 for (int i=1; i<=m; ++i) {
78 int u, v, c; scanf ("%d%d%d", &u, &v, &c);
79 if (-c > w[u][v]) w[u][v] = -c;
80 }
81 printf ("%d
", KM ());
82 }
83
84 return 0;
85 }