Not able to get the correct solution.. HELP ME!

#1

package assignmnets;

import java.util.Scanner;

public class XOR_MaximumProfit {

public static void main(String[] args) {
	// TODO Auto-generated method stub
	Scanner scn = new Scanner(System.in);
	int n1 = scn.nextInt();
	int n2 = scn.nextInt();
	int pos = 0;
	int temp = n2;
	while (temp > 0) {

		pos++;
		temp = temp >> 1;
	}
	pos--;

// System.out.println(pos);
long max_Xor = 0;
long xr = 0;
long num = (n2 - n1) + 1;
int vis = 0;
int shift = 0;
for (long i = 0; i < num; i++) {
int f_bit = getIthBit(n1, pos);
int s_bit = getIthBit(n2, pos);
xr = (f_bit ^ s_bit);
if (xr >= 1) {
max_Xor |= (1 << pos) & (~(0));
}
if (xr == 0 && vis != 0) {
if (f_bit == 0) {
int temp1 = set_Bit(n1, pos);
if (temp1 > n1 && temp1 <= n2) {
n1=temp1;
max_Xor |= (1 << pos) & (~(0));
}
}
if (s_bit == 1) {
int temp2 = set_Bit(n2, pos);
if (temp2 < n2 && temp2 >= n1) {
n2=temp2;
max_Xor |= (1 << pos) & (~(0));

				}
			}
		}
		pos--;
		vis++;

	}
	System.out.println(max_Xor);
}

private static int set_Bit(int n1, int pos) {
	// TODO Auto-generated method stub
	int mask = (1 << pos);
	return (n1 | pos);
}

public static int getIthBit(int n, int i) {
	int mask = (1 << i);
	return (n & mask);
}

}

#2

@guptadev354,

Suggested approach:

  • A simple solution is to generate all pairs, find their XOR values and finally return the maximum XOR value.

  • 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.

#3

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#4

@guptadev354,
What problem are you facing?