dlib C++ Library - max_cost_assignment_ex.cpp

// The contents of this file are in the public domain. See LICENSE_FOR_EXAMPLE_PROGRAMS.txt
/*
 
 This simple example shows how to call dlib's optimal linear assignment problem solver.
 It is an implementation of the famous Hungarian algorithm and is quite fast, operating in
 O(N^3) time.
*/
#include <dlib/optimization/max_cost_assignment.h>
#include <iostream>
using namespace std;
using namespace dlib;
int main ()
{
 // Let's imagine you need to assign N people to N jobs. Additionally, each person will make
 // your company a certain amount of money at each job, but each person has different skills
 // so they are better at some jobs and worse at others. You would like to find the best way
 // to assign people to these jobs. In particular, you would like to maximize the amount of
 // money the group makes as a whole. This is an example of an assignment problem and is
 // what is solved by the max_cost_assignment() routine.
 // 
 // So in this example, let's imagine we have 3 people and 3 jobs. We represent the amount of
 // money each person will produce at each job with a cost matrix. Each row corresponds to a
 // person and each column corresponds to a job. So for example, below we are saying that
 // person 0 will make 1ドル at job 0, 2ドル at job 1, and 6ドル at job 2. 
 matrix<int> cost(3,3);
 cost = 1, 2, 6,
 5, 3, 6,
 4, 5, 0;
 // To find out the best assignment of people to jobs we just need to call this function.
 std::vector<long> assignment = max_cost_assignment(cost);
 // This prints optimal assignments: [2, 0, 1] which indicates that we should assign
 // the person from the first row of the cost matrix to job 2, the middle row person to
 // job 0, and the bottom row person to job 1.
 for (unsigned int i = 0; i < assignment.size(); i++)
 cout << assignment[i] << std::endl;
 // This prints optimal cost: 16.0
 // which is correct since our optimal assignment is 6+5+5.
 cout << "optimal cost: " << assignment_cost(cost, assignment) << endl;
}