136 single number (for unique numbers medium)

The title means: an int array with one number appearing once and the other number appearing two times to find this unique number

Knowledge Popularization: ~: Non-arithmetic, monocular operator 1 is 0,0 to 1;

&: With arithmetic, all 1 is 1, otherwise 0

|: Or operation, all 0 is 0, otherwise 1

^: XOR operation, same as 0, different 1

Idea: The elements in the array are different or operation, then only 0 and the unique number, different or get the unique number

1 classSolution {2  Public:3     intSinglenumber (vector<int>&nums) {4         intres=0;5          for(intI=0; I<nums.size (); + +i) {6res^=Nums[i];7         }8         returnRes;9     }Ten};

Time complexity: O (N)

136 single number (for unique numbers medium)