【LeetCode】136 & 137 & 260 - Single Number I & II &III

I.

Given an array of integers, every element appears twice except for one. Find that single one.

Note:
Your algorithm should have a linear runtime complexity. Could you implement it without using extra memory?

Hide Tags： Hash Table Bit Manipulation

Hide Similar Problems： (M) Single Number II (M) Single Number III (M) Missing Number (H) Find the Duplicate Number

Solution : Xor

class Solution {
public:
int singleNumber(vector<int>& nums){
int ret=0; //it must be initialized
for(int i=0;i<nums.size();i++){
ret=ret^nums[i];
}
return ret;
}
};

II.

Given an array of integers, every element appears three times except for one. Find that single one.

Note:
Your algorithm should have a linear runtime complexity. Could you implement it without using extra memory?

Hide Tags : Bit Manipulation

Hide Similar Problems : (M) Single Number (M) Single Number III

Solution :