"Bit operations you don't know can still be used like this ."

"Bit operations you don't know can still be used like this ."
1. Calculate the number of 1 in the binary representation of a number

After a decimal number is reduced by 1, the 1 position of its decimal digit changes to 0, and the next position changes to 1. Therefore, it changes the 1 position of its decimal digit to 0. (For example, the Binary Expression of Number 6 is 00000110, And the Binary Expression of number 5 is 00000101. After performing an operation, the two digits change to 00000100 after the two digits are in phase, the number of 1 in the Binary Expression of Number 6 is reduced by one)

int countOf_1(int num){    int ans = 0;    while(num){        num &= num - 1;        ans++;    }    return ans;}

2. Determine whether a number is the N power of 2.

Determine whether a number is the N power of 2, that is, to determine whether the highest bit of a binary number is 1, and only one

bool is_2Power(int num){    num &= num - 1;    return num == 0;}

3. How many times can integer n be changed to m (the number of binary digits changed)

Int countChange (int n, int m) {return countOf_1 (n ^ m); // call the first function}

4. obtain the maximum and minimum int values.

Pair <int, int> getLimitInt () {pair <int, int> p; p. first = ~ (1 <31); // int maximum value p. second = 1 <31; // int minimum value return p ;}

5. Judge the parity of a number

To determine whether a number is an odd number, you can determine whether the second bit in the Binary Expression of a number is 1.

bool isOdd(int num){    return num & 1 == 1;}

6. Exchange the values of two numbers

In decimal, the values of two numbers a and B can be as follows: a = a + B; B = a-B; a = a-B; similarly, in binary format, you can use an exclusive or operation: a = a ^ B; B = a ^ B; a = a ^ B;

void swap(int a, int b){    a ^= b ^= a ^= b;    return ;}

7. Calculate the average value of two numbers

int getAverage(int m, int n){    return (m + n) >> 1;}

8. Calculate the m-digit reciprocal Value

int getMthN(int n, int m){    return (n >> (m - 1)) & 1;}

9. Set the m-digit to 1.

void setMthN_1(int n, int m){    n |= (1 << (m - 1));    return ;}

10. Set the MTH digit to 0.

void setMthN_0(int n, int m){    n &= ~(1 << (m - 1));    return ;}

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