13 bipartite_t *bipartite_new(int n_left, int n_right)
16 bipartite_t *gr = malloc(sizeof(*gr));
17 memset(gr, 0, sizeof(*gr));
20 gr->n_right = n_right;
21 gr->adj = malloc(n_left * sizeof(void *));
23 for(i = 0; i < n_left; ++i)
24 gr->adj[i] = bitset_malloc(n_right);
29 void bipartite_free(bipartite_t *gr)
32 for(i = 0; i < gr->n_left; ++i)
33 bitset_free(gr->adj[i]);
39 void bipartite_add(bipartite_t *gr, int i, int j)
41 assert(i < gr->n_left && j < gr->n_right);
42 bitset_set(gr->adj[i], j);
45 void bipartite_remv(bipartite_t *gr, int i, int j)
47 assert(i < gr->n_left && j < gr->n_right);
48 bitset_clear(gr->adj[i], j);
51 int bipartite_adj(const bipartite_t *gr, int i, int j)
53 assert(i < gr->n_left && j < gr->n_right);
54 return bitset_is_set(gr->adj[i], j);
57 static int apply_alternating_path(const bipartite_t *gr, int *matching,
58 bitset_t *matched_left, bitset_t *matched_right)
61 int done_something = 0;
62 bitset_t *tmp = bitset_malloc(gr->n_left);
64 for(left = 0; left < gr->n_left; ++left) {
65 bitset_t *left_adj = gr->adj[left];
68 bitset_copy(tmp, left_adj);
70 if(matching[left] >= 0) {
71 int old_right = matching[left];
73 /* Check of all neighbors of the left node are already matched.
74 * We cannot improve this edge then. */
75 if(bitset_contains(left_adj, matched_right))
78 bitset_andnot(tmp, matched_right);
79 right = bitset_next_set(tmp, 0);
83 /* We have to find another left node which has the old right
84 * one as a neighbor. */
85 for(i = 0; i < gr->n_left; ++i)
86 if(i != left && bitset_is_set(gr->adj[i], old_right))
89 /* If no such node can be found, exit. */
93 /* Else, we can improve this edge. */
94 matching[left] = right;
95 matching[i] = old_right;
96 bitset_set(matched_left, i);
97 bitset_set(matched_right, right);
102 /* We have to create a new single edge */
104 assert(!bitset_is_set(matched_left, left));
106 bitset_andnot(tmp, matched_right);
107 if(bitset_popcnt(tmp) == 0)
110 right = bitset_min(tmp);
111 assert(!bitset_is_set(matched_right, right));
112 matching[left] = right;
113 bitset_set(matched_left, left);
114 bitset_set(matched_right, right);
121 return done_something;
124 void bipartite_matching(const bipartite_t *gr, int *matching)
126 bitset_t *matched_left = bitset_malloc(gr->n_left);
127 bitset_t *matched_right = bitset_malloc(gr->n_right);
129 memset(matching, -1, gr->n_left * sizeof(int));
130 while(apply_alternating_path(gr, matching, matched_left, matched_right));
132 bitset_free(matched_left);
133 bitset_free(matched_right);
136 void bipartite_dump(FILE *f, const bipartite_t *gr)
140 for(i = 0; i < gr->n_left; ++i) {
141 bitset_fprint(f, gr->adj[i]);