package com.interview.bits;
/**
* Exercise 5.3 150 qs
*/
public class NextHigherAndNextLowerWithSameNumberBits {
public int nextHigher(int n){
int i = 1;
int first1 = 0;
//go till you find first 1
while((n & i) == 0){
i = i << 1;
first1++;
}
//count number of 1s before first 0
int count1s = 0;
while((n & i) > 0){
i = i <<1;
count1s++;
}
count1s--;
//change this first 0 after 1 to 1
n = n^i;
n = n ^ (i>>1);
int mask = ~(1<<(first1 + count1s) -1);
n = mask & n;
n = n | ((1<<count1s) -1);
return n;
}
public int nextLower(int n){
if(n ==0){
return 0;
}
int i = 1;
int first0 = 0;
while((n & i) > 0){
i = i << 1;
first0++;
}
int count0s = 0;
while((n & i) == 0){
i = i <<1;
count0s++;
}
count0s--;
//change this first 0 after 1 to 1
n = n^i;
n = n ^ (i>>1);
int mask = (1<<first0) -1;
n = n ^ mask;
n = n | (mask<<count0s);
return n;
}
public static void main(String args[]){
NextHigherAndNextLowerWithSameNumberBits nhn = new NextHigherAndNextLowerWithSameNumberBits();
System.out.println(nhn.nextHigher(94));
System.out.println(nhn.nextLower(10));
}
}