Given a non-negative number n and two values l and r. The problem is to check whether all the bits are set or not in the range l to r in the binary representation of n.
Constraint: 1 <= l <= r <= number of bits in the binary representation of n.
Input : n = 22, l = 2, r = 3 Output : Yes (22)10 = (10110)2 The bits in the range 2 to 3 are all set. Input : n = 47, l = 2, r = 5 Output : No (47)10 = (101111)2 The bits in the range 2 to 5 are all not set.
Approach: Following are the steps:
- Calculate num = ((1 << r) – 1) ^ ((1 << (l-1)) – 1). This will produce a number num having r number of bits and bits in the range l to r are the only set bits.
- Calculate new_num = n & num.
- If num == new_num, return “Yes” (all bits are set in the given range).
- Else return “No” (all bits are not set in the given range).
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Improved By : jit_t