Hello ! Can somebody explain to me how to solve this problem in O(logn) ?↵
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Given N ( N <= 10^18 ) find the number of ordered pairs (a, b) for which a ^ b = X. ( 1 <= a, b <= N )↵
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X is the first number >= N which has all it's bits equal to 1. For example if N = 5(101) then X = 7(111) and if N = 7 then X = 7.↵
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Additional challenge : X is any number between 1 and 10^18, independent of N.↵
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Problem link if somebody wants to submit : https://www.hackerearth.com/problem/algorithm/roy-and-maximum-xor/
↵
Given N ( N <= 10^18 ) find the number of ordered pairs (a, b) for which a ^ b = X. ( 1 <= a, b <= N )↵
↵
X is the first number >= N which has all it's bits equal to 1. For example if N = 5(101) then X = 7(111) and if N = 7 then X = 7.↵
↵
Additional challenge : X is any number between 1 and 10^18, independent of N.↵
↵
Problem link if somebody wants to submit : https://www.hackerearth.com/problem/algorithm/roy-and-maximum-xor/
