Single Number
Leetcode 136. Single Number
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?
class Solution {
public:
int singleNumber(vector<int>& nums) {
int res = 0;
for (int n:nums)
res ^= n;
return res;
}
};
Leetcode 137. Single Number II
Given an array of integers, every element appears three times except for one. Find that single one.
class Solution {
public:
int singleNumber(vector<int>& nums) {
int one = 0, two = 0;
for (int n: nums) {
two |= (n&one);
one ^= n;
int t = one & two;
one &= (~t);
two &= (~t);
}
return one;
}
};
Leetcode 260. Single Number III
Given an array of numbers nums, in which exactly two elements appear only once and all the other elements appear exactly twice. Find the two elements that appear only once.
For example: Given nums = [1, 2, 1, 3, 2, 5], return [3, 5].
class Solution {
public:
vector<int> singleNumber(vector<int>& nums) {
int diff = 0;
for (int n: nums) diff^=n;
diff &= -diff;
int num1= 0, num2 = 0;
for (int n:nums) {
if ((diff & n)==0) num1 ^= n;
else num2^=n;
}
return {num1, num2};
}
};