public int rangeBitwiseAnd(int m, int n) {

if (m == 0) return 0;

int res = 0;

int range = n - m + 1;

int b = 1;

for (int i=0; i<=31; i++) {

if (range <= b && (getBit(m, i) == 1 && getBit(n, i) == 1)) {

res = setBit(res, i);

}

b <<= 1;

}

return res;

}

private int setBit(int num, int pos) {

return num | (1 << pos);

}

private int getBit(int num, int pos) {

return (num & (1 << pos)) >> pos;

}

/**

public int rangeBitwiseAnd2(int m, int n) {

if(m == 0){

return 0;

}

int moveFactor = 1;

while(m != n){

m >>= 1;

n >>= 1;

moveFactor <<= 1;

}

return m * moveFactor;

}

/**

public int rangeBitwiseAnd3(int m, int n) {

while(m<n) n = n & (n-1);

return n;

}