Approach Problem

How are we to approach this problem also no constraints are provided for the same so what is the optimum time complexity that is required in this question

hello @NimeshJohari02

u can use brute force approach that will pass the test case.
another approach is this->
An efficient solution is to consider pattern of binary values from L to R. We can see that first bit from L to R either changes from 0 to 1 or it stays 1 i.e. if we take the XOR of any two numbers for maximum value their first bit will be fixed which will be same as first bit of XOR of L and R itself. After observing the technique to get first bit, we can see that if we XOR L and R, the most significant bit of this XOR will tell us the maximum value we can achieve i.e. let XOR of L and R is 1xxx where x can be 0 or 1 then maximum XOR value we can get is 1111 because from L to R we have all possible combination of xxx and it is always possible to choose these bits in such a way from two numbers such that their XOR becomes all 1.

code

#include <iostream>
using namespace std;
int main()
{
    int x,y;
    cin>>x>>y;
    int num = x^y;
    int msb=0;
    while(num!=0) {
        num=num>>1;
        msb++;
    }
    int result = 1;
    while(msb--) {
        result=result<<1;
    }
    cout<<result-1;

    return 0;
}

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