14 bipartite_t *bipartite_new(int n_left, int n_right)
17 bipartite_t *gr = xmalloc(sizeof(*gr) + n_left * sizeof(void *));
18 memset(gr, 0, sizeof(*gr));
21 gr->n_right = n_right;
22 gr->adj = (bitset_t**)(gr + 1);
24 for(i = 0; i < n_left; ++i)
25 gr->adj[i] = bitset_malloc(n_right);
30 void bipartite_free(bipartite_t *gr)
33 for(i = 0; i < gr->n_left; ++i)
34 bitset_free(gr->adj[i]);
38 void bipartite_add(bipartite_t *gr, int i, int j)
40 assert(i < gr->n_left && j < gr->n_right);
41 bitset_set(gr->adj[i], j);
44 void bipartite_remv(bipartite_t *gr, int i, int j)
46 assert(i < gr->n_left && j < gr->n_right);
47 bitset_clear(gr->adj[i], j);
50 int bipartite_adj(const bipartite_t *gr, int i, int j)
52 assert(i < gr->n_left && j < gr->n_right);
53 return bitset_is_set(gr->adj[i], j);
56 static int apply_alternating_path(const bipartite_t *gr, int *matching,
57 bitset_t *matched_left, bitset_t *matched_right)
60 int done_something = 0;
61 bitset_t *tmp = bitset_alloca(gr->n_right);
63 for(left = 0; left < gr->n_left; ++left) {
64 bitset_t *left_adj = gr->adj[left];
67 bitset_copy(tmp, left_adj);
69 if(matching[left] >= 0) {
70 int old_right = matching[left];
72 /* Check of all neighbors of the left node are already matched.
73 * We cannot improve this edge then. */
74 if(bitset_contains(left_adj, matched_right))
77 bitset_andnot(tmp, matched_right);
78 right = bitset_next_set(tmp, 0);
82 /* We have to find another left node which has the old right
83 * one as a neighbor. */
84 for(i = 0; i < gr->n_left; ++i)
85 if(i != left && bitset_is_set(gr->adj[i], old_right))
88 /* If no such node can be found, exit. */
92 /* Else, we can improve this edge. */
93 matching[left] = right;
94 matching[i] = old_right;
95 bitset_set(matched_left, i);
96 bitset_set(matched_right, right);
101 /* We have to create a new single edge */
103 assert(!bitset_is_set(matched_left, left));
105 bitset_andnot(tmp, matched_right);
106 if(bitset_popcnt(tmp) == 0)
109 right = bitset_min(tmp);
110 assert(!bitset_is_set(matched_right, right));
111 matching[left] = right;
112 bitset_set(matched_left, left);
113 bitset_set(matched_right, right);
118 return done_something;
121 void bipartite_matching(const bipartite_t *gr, int *matching)
123 bitset_t *matched_left = bitset_malloc(gr->n_left);
124 bitset_t *matched_right = bitset_malloc(gr->n_right);
126 memset(matching, -1, gr->n_left * sizeof(int));
127 while(apply_alternating_path(gr, matching, matched_left, matched_right));
129 bitset_free(matched_left);
130 bitset_free(matched_right);
133 void bipartite_dump(FILE *f, const bipartite_t *gr)
137 for(i = 0; i < gr->n_left; ++i) {
138 bitset_fprint(f, gr->adj[i]);