move min_cut, fix #1321

Signed-off-by: Nikolaj Bjorner <nbjorner@microsoft.com>

src/util/min_cut.h

@@ -0,0 +1,56 @@
+/*++
+Copyright (c) 2017 Arie Gurfinkel
+
+Module Name:
+
+    min_cut.h
+
+Abstract:
+    min cut solver
+
+Author:
+    Bernhard Gleiss
+
+Revision History:
+
+
+--*/
+
+#ifndef MIN_CUT_H_
+#define MIN_CUT_H_
+
+#include "ast/ast.h"
+#include "util/vector.h"
+
+
+class min_cut {
+public:
+    min_cut();
+
+    unsigned new_node();
+    /*
+      \brief add an edge (with unit capacity)
+    */
+    void add_edge(unsigned i, unsigned j);
+
+    void compute_min_cut(unsigned_vector& cut_nodes);
+    
+private:
+
+    typedef svector<bool> bool_vector;
+    struct edge { unsigned node; unsigned weight; edge(unsigned n, unsigned w): node(n), weight(w) {} edge(): node(0), weight(0) {} };
+    typedef svector<edge> edge_vector;
+        
+    vector<edge_vector> m_edges; // map from node to all outgoing edges together with their weights (also contains "reverse edges")
+    unsigned_vector m_d;    // approximation of distance from node to sink in residual graph
+    unsigned_vector m_pred; // predecessor-information for reconstruction of augmenting path
+    
+    void compute_initial_distances();
+    unsigned get_admissible_edge(unsigned i);
+    void augment_path();
+    void compute_distance(unsigned i);
+    void compute_reachable_nodes(bool_vector& reachable);
+    void compute_cut_and_add_lemmas(bool_vector& reachable, unsigned_vector& cut_nodes);
+};
+
+#endif