Python Program to Count number of binary strings without consecutive 1’s

Given a positive integer N, count all possible distinct binary strings of length N such that there are no consecutive 1’s.

Examples:

```Input:  N = 2
Output: 3
// The 3 strings are 00, 01, 10

Input: N = 3
Output: 5
// The 5 strings are 000, 001, 010, 100, 101```

Python3

 `# Python program to count ` `# all distinct binary strings ` `# without two consecutive 1's ` ` `  `def` `countStrings(n): ` ` `  `    ``a ``=``[``0` `for` `i ``in` `range``(n)] ` `    ``b ``=``[``0` `for` `i ``in` `range``(n)] ` `    ``a[``0``] ``=` `b[``0``] ``=` `1` `    ``for` `i ``in` `range``(``1``, n): ` `        ``a[i] ``=` `a[i``-``1``] ``+` `b[i``-``1``] ` `        ``b[i] ``=` `a[i``-``1``] ` `     `  `    ``return` `a[n``-``1``] ``+` `b[n``-``1``] ` ` `  `# Driver program to test ` `# above functions ` ` `  `print``(countStrings(``3``)) ` ` `  `# This code is contributed ` `# by Anant Agarwal. `

Output:

```5
```

Please refer complete article on Count number of binary strings without consecutive 1’s for more details!

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