Binary Search

Two Pointers

Depth-First Search, DFS

Breadth-First Search, BFS

Dynamic Programming, DP

Backtracking

Bit Manipulation

1. &：

   0 & 0 = 0
      
   0 & 1 = 0
      
   1 & 0 = 0
      
   1 & 1 = 1
   

2. XOR:

   0 ^ 0 = 0 
   0 ^ 1 = 1 
   1 ^ 0 = 1 
   1 ^ 1 = 0
   

       0101 (decimal 5)
   XOR 0011 (decimal 3)
     = 0110 (decimal 6)
   

       0010 (decimal 2)
   XOR 1010 (decimal 10)
     = 1000 (decimal 8)
   

3. |:

   0 | 0 = 0 
      
   0 | 1 = 1 
      
   1 | 0 = 1 
      
   1 | 1 = 1
   

4. &：

   0 & 0 = 0 
   0 & 1 = 0 
   1 & 0 = 0 
   1 & 1 = 1
   

5. ~：

   ~1 = 0 
   ~0 = 1
   

6. <<：

   shifts a bit pattern to the left

   左边的二进制位丢弃，右边补0

   -1 = 11111111111111111111111111111111
      
   -1 << 31 = 10000000000000000000000000000000 = -2147483648
      
   -2147483648 << 1 = 0
      
   -1 << 32 = 11111111111111111111111111111111 = -1
   32 mod 32 = 0
   so, -1 << 32 = -1 << 0 = -1
      
   -1 << 31 << 1 = 0
   

7. >>：

   shifts a bit pattern to the right, the bit pattern is given by the left-hand operand

   正数左补0，负数左补1，右边丢弃

8. >>>：

   shifts a zero into the leftmost position

   忽略符号位，空位都以0补齐