Minimum number of moves required to obtain chess like coloring.












1












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I've been preparing for a competition and there is this problem that I cannot solve. Can you please help me and also tell me how to do similar problems if they appear in the future?



Problem:



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    1












    $begingroup$


    I've been preparing for a competition and there is this problem that I cannot solve. Can you please help me and also tell me how to do similar problems if they appear in the future?



    Problem:



    Please click on the link because I can't send it by inserting it










    share|cite|improve this question











    $endgroup$















      1












      1








      1


      1



      $begingroup$


      I've been preparing for a competition and there is this problem that I cannot solve. Can you please help me and also tell me how to do similar problems if they appear in the future?



      Problem:



      Please click on the link because I can't send it by inserting it










      share|cite|improve this question











      $endgroup$




      I've been preparing for a competition and there is this problem that I cannot solve. Can you please help me and also tell me how to do similar problems if they appear in the future?



      Problem:



      Please click on the link because I can't send it by inserting it







      geometry arithmetic






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      share|cite|improve this question













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      edited Jan 3 at 3:02









      David G. Stork

      10.4k21332




      10.4k21332










      asked Jan 3 at 1:15









      The ThunderkingThe Thunderking

      61




      61






















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          $begingroup$

          I am unsure what the "general procedure" should be for this kind of problem, but I can help for this specific one.



          Note that for the $5times 5$ square shown, there are $12$ black squares. Since none of the black squares are neighbors, we know that the minimum number of moves to take the starting configuration to the final configuration is at least $12$. Thus, if we can demonstrate a sequence of moves of length $12$ which accomplishes our goal, we will have proven that the minimum is exactly $12$.



          SPOILERS AHEAD!




          So what sequence of $12$ moves accomplishes our goal? Well, we can "click" each corner twice to get $8$ black squares while leaving the corners white (since two "clicks" will negate each other on the same square), and we can get the remaining $4$ black squares in the center by "clicking" the very middle square $4$ times.







          share|cite|improve this answer











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            1 Answer
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            1 Answer
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            active

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            active

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            4












            $begingroup$

            I am unsure what the "general procedure" should be for this kind of problem, but I can help for this specific one.



            Note that for the $5times 5$ square shown, there are $12$ black squares. Since none of the black squares are neighbors, we know that the minimum number of moves to take the starting configuration to the final configuration is at least $12$. Thus, if we can demonstrate a sequence of moves of length $12$ which accomplishes our goal, we will have proven that the minimum is exactly $12$.



            SPOILERS AHEAD!




            So what sequence of $12$ moves accomplishes our goal? Well, we can "click" each corner twice to get $8$ black squares while leaving the corners white (since two "clicks" will negate each other on the same square), and we can get the remaining $4$ black squares in the center by "clicking" the very middle square $4$ times.







            share|cite|improve this answer











            $endgroup$


















              4












              $begingroup$

              I am unsure what the "general procedure" should be for this kind of problem, but I can help for this specific one.



              Note that for the $5times 5$ square shown, there are $12$ black squares. Since none of the black squares are neighbors, we know that the minimum number of moves to take the starting configuration to the final configuration is at least $12$. Thus, if we can demonstrate a sequence of moves of length $12$ which accomplishes our goal, we will have proven that the minimum is exactly $12$.



              SPOILERS AHEAD!




              So what sequence of $12$ moves accomplishes our goal? Well, we can "click" each corner twice to get $8$ black squares while leaving the corners white (since two "clicks" will negate each other on the same square), and we can get the remaining $4$ black squares in the center by "clicking" the very middle square $4$ times.







              share|cite|improve this answer











              $endgroup$
















                4












                4








                4





                $begingroup$

                I am unsure what the "general procedure" should be for this kind of problem, but I can help for this specific one.



                Note that for the $5times 5$ square shown, there are $12$ black squares. Since none of the black squares are neighbors, we know that the minimum number of moves to take the starting configuration to the final configuration is at least $12$. Thus, if we can demonstrate a sequence of moves of length $12$ which accomplishes our goal, we will have proven that the minimum is exactly $12$.



                SPOILERS AHEAD!




                So what sequence of $12$ moves accomplishes our goal? Well, we can "click" each corner twice to get $8$ black squares while leaving the corners white (since two "clicks" will negate each other on the same square), and we can get the remaining $4$ black squares in the center by "clicking" the very middle square $4$ times.







                share|cite|improve this answer











                $endgroup$



                I am unsure what the "general procedure" should be for this kind of problem, but I can help for this specific one.



                Note that for the $5times 5$ square shown, there are $12$ black squares. Since none of the black squares are neighbors, we know that the minimum number of moves to take the starting configuration to the final configuration is at least $12$. Thus, if we can demonstrate a sequence of moves of length $12$ which accomplishes our goal, we will have proven that the minimum is exactly $12$.



                SPOILERS AHEAD!




                So what sequence of $12$ moves accomplishes our goal? Well, we can "click" each corner twice to get $8$ black squares while leaving the corners white (since two "clicks" will negate each other on the same square), and we can get the remaining $4$ black squares in the center by "clicking" the very middle square $4$ times.








                share|cite|improve this answer














                share|cite|improve this answer



                share|cite|improve this answer








                edited Jan 3 at 1:35

























                answered Jan 3 at 1:28









                ItsJustASeriesBroItsJustASeriesBro

                1563




                1563






























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