Time and space complexity

[kumawatnitesh093 (Nitesh Kumawat)]

Find the time complexity of the given code.

int count = 0;
for (int i = N; i > 0; i /= 2)
for (int j = 0; j < i; j++)
count++;

O(log N)

O(N)

O(N*log N)

O(N^2)

what is the answer for this question chec once?

[talhashamim001 (Talha Shamim)]

@kumawatnitesh093

int count = 0;
for (int i = N; i > 0; i /= 2)
for (int j = 0; j < i; j++)
count++;

@kumawatnitesh093,
For a input integer n, the innermost statement of fun() is executed following times.

n + n/2 + n/4 + … 1

So time complexity T(n) can be written as

T(n) = O(n + n/2 + n/4 + … 1) = O(n)