title: TSP - Branch and bound
body: <p>I'm trying to solve the TSP with Branch and bound algorithm.</p>
  
  <p>I must build a matrix with costs but I have this problem:
  I have city with coordinates x and y.</p>
  
  <p>The cost of traveling is <code>ceil(ceil(sqrt((x1-x2)^2+(y1-y2)^2))/v)</code> + days spent in the city.
  V is speed.</p>
  
  <p>Days spent in the city depends from day when w comes to the city. 
  For example if we arrived on Monday(t1) to city 1, we stay for 9 days but if we arrived on Tuesday, then we stay in the city for 4 days.</p>
  
  <pre><code>         x   y   t1 .        t7
  city 1. 79 -36   9 4 8 5 5 7 8
  city 2. 8  67    6 9 2 1 9 9 1
  city 3. 29 57    7 5 10 8 10 9 4
  </code></pre>
  
  <p>How can I solve this problem using branch and bound algorithm?</p>