Bitwise AND of Numbers Range


Problem Statement :


Code
Testcase
Test Result
Test Result
201. Bitwise AND of Numbers Range
Medium
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Given two integers left and right that represent the range [left, right], return the bitwise AND of all numbers in this range, inclusive.

 

Example 1:

Input: left = 5, right = 7
Output: 4
Example 2:

Input: left = 0, right = 0
Output: 0
Example 3:

Input: left = 1, right = 2147483647
Output: 0
 

Constraints:

0 <= left <= right <= 231 - 1


Solution :



title-img 


                            Solution in C :

int rangeBitwiseAnd(int m, int n)
{
	if (0 == m)
		return 0;
	int k = (m & n);
	int bit[32] = { 0 }; 
	int i = 31, ret = 0;
	int dif = n - m;
	int bitdif = 0;
	for (; i >= 0; --i) //transfer (m & n) into 32 bit array.
	{
		if (k & 1)
			bit[i] = 1;
		k = k >> 1;
		if (!k)
			break;
	}

	for (; dif; dif = dif >> 1, ++bitdif); //calculate the binary 'length' of 'm-n'

	for (i = 31; i > (31 - bitdif); --i)  //let all digits (started from tail) in the 'length' = 0
		bit[i] = 0;

	for (i; i >= 0; --i)
	{
		if (bit[i])
			ret += 1 << (31 - i);
	}
	return ret;
}
                        


                        Solution in C++ :

class Solution {
public:
    int rangeBitwiseAnd(int left, int right) {
        int cnt = 0;
        while (left != right) {
            left >>= 1;
            right >>= 1;
            cnt++;
        }
        return (left << cnt);
    }
};
                    


                        Solution in Java :

class Solution {
    public int rangeBitwiseAnd(int left, int right) {
        int cnt = 0;
        while (left != right) {
            left >>= 1;
            right >>= 1;
            cnt++;
        }
        return (left << cnt);
    }
}
                    


                        Solution in Python : 
                            
class Solution:
    def rangeBitwiseAnd(self, left: int, right: int) -> int:
        cnt = 0
        while left != right:
            left >>= 1
            right >>= 1
            cnt += 1
        return left << cnt


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