Am I on the right path solving this problem from 11 n-bits?











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So the problem is to find how many 11-bit strings will have no consecutive three zeroes.



I have used recurrence to solve this problem. I set $T(n)$ to be the number of strings of size n that there will be no consecutive three zeroes. If the firsst digit is filled with 1, then you get $T(n-1)$ that can be filled and then you get $T(n-2) and T(n-3)$ for the second and third boxes.



T1- 2 (can be either 0 or 1)
T2 - 4 (00,01,10,100)
T3 - 7 (991,010,011,100,101,110, 111)



Now is when I start adding up the previous three terms up
T4 = T1+T2+T3 = 13



T5 = T2+T3+T4 = 24



I keep doing this unitl I get to T11



T11 - T10 + T9+ t8 = 927 11 bit strings with no consecutive three 0s in a row










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  • The total number of 11-bit strings is $2^{11}$. Now, consider the ones that contains "000", We can count strings that has "000" by thinking of "000" as one bit a 9-bit string. Does this help?
    – mathnoob
    20 hours ago












  • @mathnoob - that approach is full of pitfalls, and ends up much more complicated than the approach in the question. Try that approach with n=4 or n=5, for example. Accounting for all the double-counting is way more complicated than this approach.
    – Daniel Martin
    19 hours ago










  • A similar problem (not a duplicate), with solution, can be found here: math.stackexchange.com/questions/3001026/…
    – awkward
    14 hours ago















up vote
1
down vote

favorite












So the problem is to find how many 11-bit strings will have no consecutive three zeroes.



I have used recurrence to solve this problem. I set $T(n)$ to be the number of strings of size n that there will be no consecutive three zeroes. If the firsst digit is filled with 1, then you get $T(n-1)$ that can be filled and then you get $T(n-2) and T(n-3)$ for the second and third boxes.



T1- 2 (can be either 0 or 1)
T2 - 4 (00,01,10,100)
T3 - 7 (991,010,011,100,101,110, 111)



Now is when I start adding up the previous three terms up
T4 = T1+T2+T3 = 13



T5 = T2+T3+T4 = 24



I keep doing this unitl I get to T11



T11 - T10 + T9+ t8 = 927 11 bit strings with no consecutive three 0s in a row










share|cite|improve this question







New contributor




Noob Coder is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.




















  • The total number of 11-bit strings is $2^{11}$. Now, consider the ones that contains "000", We can count strings that has "000" by thinking of "000" as one bit a 9-bit string. Does this help?
    – mathnoob
    20 hours ago












  • @mathnoob - that approach is full of pitfalls, and ends up much more complicated than the approach in the question. Try that approach with n=4 or n=5, for example. Accounting for all the double-counting is way more complicated than this approach.
    – Daniel Martin
    19 hours ago










  • A similar problem (not a duplicate), with solution, can be found here: math.stackexchange.com/questions/3001026/…
    – awkward
    14 hours ago













up vote
1
down vote

favorite









up vote
1
down vote

favorite











So the problem is to find how many 11-bit strings will have no consecutive three zeroes.



I have used recurrence to solve this problem. I set $T(n)$ to be the number of strings of size n that there will be no consecutive three zeroes. If the firsst digit is filled with 1, then you get $T(n-1)$ that can be filled and then you get $T(n-2) and T(n-3)$ for the second and third boxes.



T1- 2 (can be either 0 or 1)
T2 - 4 (00,01,10,100)
T3 - 7 (991,010,011,100,101,110, 111)



Now is when I start adding up the previous three terms up
T4 = T1+T2+T3 = 13



T5 = T2+T3+T4 = 24



I keep doing this unitl I get to T11



T11 - T10 + T9+ t8 = 927 11 bit strings with no consecutive three 0s in a row










share|cite|improve this question







New contributor




Noob Coder is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.











So the problem is to find how many 11-bit strings will have no consecutive three zeroes.



I have used recurrence to solve this problem. I set $T(n)$ to be the number of strings of size n that there will be no consecutive three zeroes. If the firsst digit is filled with 1, then you get $T(n-1)$ that can be filled and then you get $T(n-2) and T(n-3)$ for the second and third boxes.



T1- 2 (can be either 0 or 1)
T2 - 4 (00,01,10,100)
T3 - 7 (991,010,011,100,101,110, 111)



Now is when I start adding up the previous three terms up
T4 = T1+T2+T3 = 13



T5 = T2+T3+T4 = 24



I keep doing this unitl I get to T11



T11 - T10 + T9+ t8 = 927 11 bit strings with no consecutive three 0s in a row







recurrence-relations






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  • The total number of 11-bit strings is $2^{11}$. Now, consider the ones that contains "000", We can count strings that has "000" by thinking of "000" as one bit a 9-bit string. Does this help?
    – mathnoob
    20 hours ago












  • @mathnoob - that approach is full of pitfalls, and ends up much more complicated than the approach in the question. Try that approach with n=4 or n=5, for example. Accounting for all the double-counting is way more complicated than this approach.
    – Daniel Martin
    19 hours ago










  • A similar problem (not a duplicate), with solution, can be found here: math.stackexchange.com/questions/3001026/…
    – awkward
    14 hours ago


















  • The total number of 11-bit strings is $2^{11}$. Now, consider the ones that contains "000", We can count strings that has "000" by thinking of "000" as one bit a 9-bit string. Does this help?
    – mathnoob
    20 hours ago












  • @mathnoob - that approach is full of pitfalls, and ends up much more complicated than the approach in the question. Try that approach with n=4 or n=5, for example. Accounting for all the double-counting is way more complicated than this approach.
    – Daniel Martin
    19 hours ago










  • A similar problem (not a duplicate), with solution, can be found here: math.stackexchange.com/questions/3001026/…
    – awkward
    14 hours ago
















The total number of 11-bit strings is $2^{11}$. Now, consider the ones that contains "000", We can count strings that has "000" by thinking of "000" as one bit a 9-bit string. Does this help?
– mathnoob
20 hours ago






The total number of 11-bit strings is $2^{11}$. Now, consider the ones that contains "000", We can count strings that has "000" by thinking of "000" as one bit a 9-bit string. Does this help?
– mathnoob
20 hours ago














@mathnoob - that approach is full of pitfalls, and ends up much more complicated than the approach in the question. Try that approach with n=4 or n=5, for example. Accounting for all the double-counting is way more complicated than this approach.
– Daniel Martin
19 hours ago




@mathnoob - that approach is full of pitfalls, and ends up much more complicated than the approach in the question. Try that approach with n=4 or n=5, for example. Accounting for all the double-counting is way more complicated than this approach.
– Daniel Martin
19 hours ago












A similar problem (not a duplicate), with solution, can be found here: math.stackexchange.com/questions/3001026/…
– awkward
14 hours ago




A similar problem (not a duplicate), with solution, can be found here: math.stackexchange.com/questions/3001026/…
– awkward
14 hours ago















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