Number of solutions to a Linear equation $a_1(x-1) + a_2(x-2) + a_3(x-3) + . . . +a_{x-1} = x$












0












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$$a_1(x-1) + a_2(x-2) + a_3(x-3) + . . . +a_{x-1} = x$$
Where $a_i = (1 quad or quad 0)$



I was thinking if there exists some solution that takes only O($N$) linear time computation.










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$endgroup$








  • 1




    $begingroup$
    Can you look at your sum again i don't think the last term is $a_{x-1}$. If it is i don't understand what terms are in the "+...+". Also, what is the relation between the number of solutions (question in title) and computation time?
    $endgroup$
    – TheD0ubleT
    Dec 15 '18 at 9:00










  • $begingroup$
    I missed that $a_i$ is either 0 or 1. So what I want to count the number of ways a number X can be represented as sum of values lesser than X, without repetition.
    $endgroup$
    – Dragon Surfer
    Dec 15 '18 at 14:40


















0












$begingroup$


$$a_1(x-1) + a_2(x-2) + a_3(x-3) + . . . +a_{x-1} = x$$
Where $a_i = (1 quad or quad 0)$



I was thinking if there exists some solution that takes only O($N$) linear time computation.










share|cite|improve this question











$endgroup$








  • 1




    $begingroup$
    Can you look at your sum again i don't think the last term is $a_{x-1}$. If it is i don't understand what terms are in the "+...+". Also, what is the relation between the number of solutions (question in title) and computation time?
    $endgroup$
    – TheD0ubleT
    Dec 15 '18 at 9:00










  • $begingroup$
    I missed that $a_i$ is either 0 or 1. So what I want to count the number of ways a number X can be represented as sum of values lesser than X, without repetition.
    $endgroup$
    – Dragon Surfer
    Dec 15 '18 at 14:40
















0












0








0





$begingroup$


$$a_1(x-1) + a_2(x-2) + a_3(x-3) + . . . +a_{x-1} = x$$
Where $a_i = (1 quad or quad 0)$



I was thinking if there exists some solution that takes only O($N$) linear time computation.










share|cite|improve this question











$endgroup$




$$a_1(x-1) + a_2(x-2) + a_3(x-3) + . . . +a_{x-1} = x$$
Where $a_i = (1 quad or quad 0)$



I was thinking if there exists some solution that takes only O($N$) linear time computation.







linear-algebra






share|cite|improve this question















share|cite|improve this question













share|cite|improve this question




share|cite|improve this question








edited Dec 15 '18 at 14:38







Dragon Surfer

















asked Dec 15 '18 at 8:04









Dragon SurferDragon Surfer

7416




7416








  • 1




    $begingroup$
    Can you look at your sum again i don't think the last term is $a_{x-1}$. If it is i don't understand what terms are in the "+...+". Also, what is the relation between the number of solutions (question in title) and computation time?
    $endgroup$
    – TheD0ubleT
    Dec 15 '18 at 9:00










  • $begingroup$
    I missed that $a_i$ is either 0 or 1. So what I want to count the number of ways a number X can be represented as sum of values lesser than X, without repetition.
    $endgroup$
    – Dragon Surfer
    Dec 15 '18 at 14:40
















  • 1




    $begingroup$
    Can you look at your sum again i don't think the last term is $a_{x-1}$. If it is i don't understand what terms are in the "+...+". Also, what is the relation between the number of solutions (question in title) and computation time?
    $endgroup$
    – TheD0ubleT
    Dec 15 '18 at 9:00










  • $begingroup$
    I missed that $a_i$ is either 0 or 1. So what I want to count the number of ways a number X can be represented as sum of values lesser than X, without repetition.
    $endgroup$
    – Dragon Surfer
    Dec 15 '18 at 14:40










1




1




$begingroup$
Can you look at your sum again i don't think the last term is $a_{x-1}$. If it is i don't understand what terms are in the "+...+". Also, what is the relation between the number of solutions (question in title) and computation time?
$endgroup$
– TheD0ubleT
Dec 15 '18 at 9:00




$begingroup$
Can you look at your sum again i don't think the last term is $a_{x-1}$. If it is i don't understand what terms are in the "+...+". Also, what is the relation between the number of solutions (question in title) and computation time?
$endgroup$
– TheD0ubleT
Dec 15 '18 at 9:00












$begingroup$
I missed that $a_i$ is either 0 or 1. So what I want to count the number of ways a number X can be represented as sum of values lesser than X, without repetition.
$endgroup$
– Dragon Surfer
Dec 15 '18 at 14:40






$begingroup$
I missed that $a_i$ is either 0 or 1. So what I want to count the number of ways a number X can be represented as sum of values lesser than X, without repetition.
$endgroup$
– Dragon Surfer
Dec 15 '18 at 14:40












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