1 Topic Description
1.1 English Description
Given two integers a and b, return the sum of the two integers without using the operators + and -.
Example 1:
Input: a = 1, b = 2
Output: 3
Example 2:
Input: a = 2, b = 3
Output: 5
1.2 Chinese Description
Given two integers, sum them without using the +/- operators.
2 solution
2.1 Solution 1-bit operation
Use bitwise operations and recursion.
For example, 2 + 3 = 5; The binary of 5 is 0101.
The operation process is as follows:
- Two to the third is equal to the sum of two plus three, zero one.
2^3 is 0010 ^ 0011 ------- 0001Copy the code- We find that 2&3 is equal to a regular number, and that a shift of 1 to the left is the carry of the final result.
2&3 is 0010&0011 -------- 0010Copy the code- The result of 2&3 is shifted one bit to the left to get the carry of the final result.
0010 << 1 = 0100
Copy the code- 0100 or 0001.
0100
^ 0001
-------
0101
Copy the code- Loop until the carry number is 0.
2.2 code
Public static int getSum(int a,int b){if(b == 0) return a; Int i1 = a ^ b; Int i2 = a & b; Int i3 = i2 << 1; Return getSum(i1,i3); }Copy the code