Flip Bits - Lintcode Java | Welkin Lan

Flip Bits – Lintcode Java | Welkin Lan

Determine the number of bits required to flip if you want to convert integer n to integer m.

Example

Given n = 31 (11111), m = 14 (01110), return 2.

Note

Both n and m are 32-bit integers.

public static int bitSwapRequired(int a, int b) {

if (a == b) {

return 0;

}

int bit = a ^ b;

int count = 0;

// integer has 32 bits

int number = 32;

// you cannot just check bit > 0 in the while statement

// because a or b maybe negative number

while (number > 0) {

count += bit & 1;

bit = bit >> 1;

number--;

}

return count;

}

http://www.ithao123.cn/content-10354641.html

    public static int bitSwapRequired(int a, int b) {
        int c = a^b;
        int count = 0;
        while(c!=0){
            count += c&1;
            c=c>>>1;
        }
        return count;
    }

    public static int bitSwapRequired(int a, int b) {
        int c = a^b;
        int count = 0;
        while(c!=0){
            c = c&(c-1);
            count++;
        }
        return count;
    }

    public static int bitSwapRequired(int a, int b) {
        // write your code here
        int count=0;
        while(a!=0 || b!=0){
            int ai = a&1;
            int bi = b&1;
            if(ai==1 && bi==0 || ai==0 && bi==1)
                count++;
            a = a>>>1;
            b = b>>>1;
        }
        return count;
    }

http://sidbai.github.io/2015/06/18/Flip-Bits/

    int bitSwapRequired(int a, int b) {
        int ret = a ^ b;
        ret = ((ret & 0xaaaaaaaa) >> 1) + (ret & 0x55555555);
        ret = ((ret & 0xcccccccc) >> 2) + (ret & 0x33333333);
        ret = ((ret & 0xf0f0f0f0) >> 4) + (ret & 0x0f0f0f0f);
        ret = ((ret & 0xff00ff00) >> 8) + (ret & 0x00ff00ff);
        ret = ((ret & 0xffff0000) >> 16) + (ret & 0x0000ffff);
        return ret;
    }

http://blog.csdn.net/wutingyehe/article/details/46635767
public static int bitSwapRequired(int a, int b) { int c = a ^ b; int count = 0; if (c < 0) { count++; c = Integer.MIN_VALUE ^ c; //??? } while(c != 0) { count += c%2; c = c/2; } return count; }
Read full article from Flip Bits – Lintcode Java | Welkin Lan