/* -*- mode: C++; indent-tabs-mode: nil; -*-

 *

 * This file is a part of LEMON, a generic C++ optimization library.

 *

 * Copyright (C) 2003-2009

 * Egervary Jeno Kombinatorikus Optimalizalasi Kutatocsoport

 * (Egervary Research Group on Combinatorial Optimization, EGRES).

 *

 * Permission to use, modify and distribute this software is granted

 * provided that this copyright notice appears in all copies. For

 * precise terms see the accompanying LICENSE file.

 *

 * This software is provided "AS IS" with no warranty of any kind,

 * express or implied, and with no claim as to its suitability for any

 * purpose.

 *

 */

#include <iostream>

#include "test_tools.h"

#include <lemon/smart_graph.h>

#include <lemon/preflow.h>

#include <lemon/concepts/digraph.h>

#include <lemon/concepts/maps.h>

#include <lemon/lgf_reader.h>

#include <lemon/elevator.h>

using namespace lemon;

char test_lgf[] =

  "@nodes\n"

  "label\n"

  "0\n"

  "1\n"

  "2\n"

  "3\n"

  "4\n"

  "5\n"

  "6\n"

  "7\n"

  "8\n"

  "9\n"

  "@arcs\n"

  "    label capacity\n"

  "0 1 0     20\n"

  "0 2 1     0\n"

  "1 1 2     3\n"

  "1 2 3     8\n"

  "1 3 4     8\n"

  "2 5 5     5\n"

  "3 2 6     5\n"

  "3 5 7     5\n"

  "3 6 8     5\n"

  "4 3 9     3\n"

  "5 7 10    3\n"

  "5 6 11    10\n"

  "5 8 12    10\n"

  "6 8 13    8\n"

  "8 9 14    20\n"

  "8 1 15    5\n"

  "9 5 16    5\n"

  "@attributes\n"

  "source 1\n"

  "target 8\n";

void checkPreflowCompile()

{

  typedef int VType;

  typedef concepts::Digraph Digraph;

  typedef Digraph::Node Node;

  typedef Digraph::Arc Arc;

  typedef concepts::ReadMap<Arc,VType> CapMap;

  typedef concepts::ReadWriteMap<Arc,VType> FlowMap;

  typedef concepts::WriteMap<Node,bool> CutMap;

  typedef Elevator<Digraph, Digraph::Node> Elev;

  typedef LinkedElevator<Digraph, Digraph::Node> LinkedElev;

  Digraph g;

  Node n;

  Arc e;

  CapMap cap;

  FlowMap flow;

  CutMap cut;

  VType v;

  bool b;

  typedef Preflow<Digraph, CapMap>

            ::SetFlowMap<FlowMap>

            ::SetElevator<Elev>

            ::SetStandardElevator<LinkedElev>

            ::Create PreflowType;

  PreflowType preflow_test(g, cap, n, n);

  const PreflowType& const_preflow_test = preflow_test;

  preflow_test

    .capacityMap(cap)

    .flowMap(flow)

    .source(n)

    .target(n);

  preflow_test.init();

  preflow_test.init(cap);

  preflow_test.startFirstPhase();

  preflow_test.startSecondPhase();

  preflow_test.run();

  preflow_test.runMinCut();

  v = const_preflow_test.flowValue();

  v = const_preflow_test.flow(e);

  const FlowMap& fm = const_preflow_test.flowMap();

  b = const_preflow_test.minCut(n);

  const_preflow_test.minCutMap(cut);

  ignore_unused_variable_warning(fm);

}

int cutValue (const SmartDigraph& g,

              const SmartDigraph::NodeMap<bool>& cut,

              const SmartDigraph::ArcMap<int>& cap) {

  int c=0;

  for(SmartDigraph::ArcIt e(g); e!=INVALID; ++e) {

    if (cut[g.source(e)] && !cut[g.target(e)]) c+=cap[e];

  }

  return c;

}

bool checkFlow(const SmartDigraph& g,

               const SmartDigraph::ArcMap<int>& flow,

               const SmartDigraph::ArcMap<int>& cap,

               SmartDigraph::Node s, SmartDigraph::Node t) {

  for (SmartDigraph::ArcIt e(g); e != INVALID; ++e) {

    if (flow[e] < 0 || flow[e] > cap[e]) return false;

  }

  for (SmartDigraph::NodeIt n(g); n != INVALID; ++n) {

    if (n == s || n == t) continue;

    int sum = 0;

    for (SmartDigraph::OutArcIt e(g, n); e != INVALID; ++e) {

      sum += flow[e];

    }

    for (SmartDigraph::InArcIt e(g, n); e != INVALID; ++e) {

      sum -= flow[e];

    }

    if (sum != 0) return false;

  }

  return true;

}

int main() {

  typedef SmartDigraph Digraph;

  typedef Digraph::Node Node;

  typedef Digraph::NodeIt NodeIt;

  typedef Digraph::ArcIt ArcIt;

  typedef Digraph::ArcMap<int> CapMap;

  typedef Digraph::ArcMap<int> FlowMap;

  typedef Digraph::NodeMap<bool> CutMap;

  typedef Preflow<Digraph, CapMap> PType;

  Digraph g;

  Node s, t;

  CapMap cap(g);

  std::istringstream input(test_lgf);

  DigraphReader<Digraph>(g,input).

    arcMap("capacity", cap).

    node("source",s).

    node("target",t).

    run();

  PType preflow_test(g, cap, s, t);

  preflow_test.run();

  check(checkFlow(g, preflow_test.flowMap(), cap, s, t),

        "The flow is not feasible.");

  CutMap min_cut(g);

  preflow_test.minCutMap(min_cut);

  int min_cut_value=cutValue(g,min_cut,cap);

  check(preflow_test.flowValue() == min_cut_value,

        "The max flow value is not equal to the three min cut values.");

  FlowMap flow(g);

  for(ArcIt e(g); e!=INVALID; ++e) flow[e] = preflow_test.flowMap()[e];

  int flow_value=preflow_test.flowValue();

  for(ArcIt e(g); e!=INVALID; ++e) cap[e]=2*cap[e];

  preflow_test.init(flow);

  preflow_test.startFirstPhase();

  CutMap min_cut1(g);

  preflow_test.minCutMap(min_cut1);

  min_cut_value=cutValue(g,min_cut1,cap);

  check(preflow_test.flowValue() == min_cut_value &&

        min_cut_value == 2*flow_value,

        "The max flow value or the min cut value is wrong.");

  preflow_test.startSecondPhase();

  check(checkFlow(g, preflow_test.flowMap(), cap, s, t),

        "The flow is not feasible.");

  CutMap min_cut2(g);

  preflow_test.minCutMap(min_cut2);

  min_cut_value=cutValue(g,min_cut2,cap);

  check(preflow_test.flowValue() == min_cut_value &&

        min_cut_value == 2*flow_value,

        "The max flow value or the three min cut values were not doubled");

  preflow_test.flowMap(flow);

  NodeIt tmp1(g,s);

  ++tmp1;

  if ( tmp1 != INVALID ) s=tmp1;

  NodeIt tmp2(g,t);

  ++tmp2;

  if ( tmp2 != INVALID ) t=tmp2;

  preflow_test.source(s);

  preflow_test.target(t);

  preflow_test.run();

  CutMap min_cut3(g);

  preflow_test.minCutMap(min_cut3);

  min_cut_value=cutValue(g,min_cut3,cap);

  check(preflow_test.flowValue() == min_cut_value,

        "The max flow value or the three min cut values are incorrect.");

  return 0;

}