461. Hamming Distance【数学|位运算】

2017/3/14 15:23:55

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The Hamming distance between two integers is the number of positions at which the corresponding bits are different.

Given two integers x and y, calculate the Hamming distance.

 

题目要求：求两个数字二进制位中同一位置不同bit的个数。

解法1  Java    利用1的移位依次匹配是否对应位为1，统计为1的个数。

 

public class Solution {
    public int hammingDistance(int x, int y) {
        x ^= y;
    	int count = 0;
    	for ( int i=0;i<32;i++ )
    		count = (1<<i & x ) !=0 ? count+1 : count;
    	return count;
    }
}

 

解法2 Java   利用 a &= a-1 依次去掉最后一个1，统计循环次数。

public class Solution {
    public int hammingDistance(int x, int y) {
        x ^= y;
    	int count = 0;
    	while( x != 0  ){
    		x &= x - 1;
    		count++;
    	}
    	return count;
    }
}