Given a positive integer N, count all possible distinct binary strings of length N such that there are no consecutive 1’s. Output your answer modulo 10^9 + 7.
N = 3
Explanation: 5 strings are (000,
001, 010, 100, 101).
N = 2
Explanation: 3 strings are
Complete the function countStrings() which takes single integer n, as input parameters and returns an integer denoting the answer. You don't to print answer or take inputs.
Expected Time Complexity: O(N)
Expected Auxiliary Space: O(N)
1 ≤ N ≤ 105
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