LeetCode - Bitwise AND of Numbers Range

Bitwise AND of Numbers Range

//
public int rangeBitwiseAnd(int m, int n) {
        while(m<n) n = n & (n-1);
        return n;
    }

//
 public int rangeBitwiseAnd(int m, int n) {
        return (n > m) ? (rangeBitwiseAnd(m/2, n/2) << 1) : m;
    }

//
public int rangeBitwiseAnd(int m, int n) {
        int k = m ^ n;
        int i = 30;
        while(i>=0 && ((k >> i) & 1) == 0){
            i--;
        }
        return n & ~((1 << (i+1)) - 1);
    }
    
//
public int rangeBitwiseAnd(int m, int n) {
        int ret = 0;
        for(int i=30; i>=0; i--){
            int low = 1 << i;
            if(m >= low && n >= low){
                ret += low;
                m -= low;
                n -= low;
            }else if(m < low && n < low){
                continue;
            }else {
                break;
            }
        }
        return ret;
    }