mv util/lp to math/lp

Signed-off-by: Lev Nachmanson <levnach@hotmail.com>

src/math/lp/int_set.h

@@ -0,0 +1,81 @@
+/*++
+Copyright (c) 2017 Microsoft Corporation
+
+Module Name:
+
+    <name>
+
+Abstract:
+
+    <abstract>
+
+Author:
+
+    Lev Nachmanson (levnach)
+
+Revision History:
+
+
+--*/
+#pragma once
+#include "util/vector.h"
+#include "math/lp/indexed_vector.h"
+#include <ostream>
+namespace lp {
+// serves at a set of non-negative integers smaller than the set size
+class int_set {
+    vector<int> m_data;
+public:
+    vector<int> m_index;
+    int_set(unsigned size): m_data(size, -1) {}
+    int_set() {}
+    bool contains(unsigned j) const {
+        if (j >= m_data.size())
+            return false;
+        return m_data[j] >= 0;
+    }
+    void insert(unsigned j) {
+        lp_assert(j < m_data.size());
+        if (contains(j)) return;
+        m_data[j] = m_index.size();
+        m_index.push_back(j);
+    }
+    void erase(unsigned j) {
+        if (!contains(j)) return;
+        unsigned pos_j = m_data[j];
+        unsigned last_pos = m_index.size() - 1;
+        int last_j = m_index[last_pos];
+        if (last_pos != pos_j) {
+            // move last to j spot
+            m_data[last_j] = pos_j;
+            m_index[pos_j] = last_j;
+        }
+        m_index.pop_back();
+        m_data[j] = -1;
+    }
+
+    void resize(unsigned size) {
+        m_data.resize(size, -1);
+    }
+
+    void increase_size_by_one() {
+        resize(m_data.size() + 1);
+    }
+
+    unsigned data_size() const {  return m_data.size(); }
+    unsigned size() const { return m_index.size();}
+    bool is_empty() const { return size() == 0; }
+    void clear() {
+        for (unsigned j : m_index)
+            m_data[j] = -1;
+        m_index.resize(0);
+    }
+    void print(std::ostream & out ) const {
+        for (unsigned j : m_index) {
+            out << j << " ";
+        }
+        out << std::endl;
+    }
+    
+};
+}