Add bipartite matching

Signed-off-by: Bruno Freitas Tissei <bft15@inf.ufpr.br>

graph/bipartite_match.cpp

+/**
+ * Bipartite Matching (simplified Ford-Fulkerson)
+ *
+ * Complexity (Time): O(n + m)
+ * Complexity (Space): O(n + m)
+ */
+
+vector<int> graph[MAX];
+int cont[MAX], match[MAX];
+
+// Find match for x
+int dfs(int x) {
+  if (cont[x])
+    return 0;
+
+  cont[x] = 1;
+  for (auto i : graph[x])
+    if (match[i] == -1 || dfs(match[v])) {
+      match[i] = x;
+      return 1;
+    }
+
+  return 0;
+}
+
+// Return number of left elements in matching and fills match array with the 
+// match itself (match[right_i] = left_i)
+int bipartite_matching(int n) {
+  int ans = 0;
+  memset(match, -1, sizeof match);
+
+  for (int i = 0; i < n; ++i) {
+    memset(cont, 0, sizeof cont);
+    ans += dfs(i);
+  }
+
+  return ans;
+}