Single Number II Leetcode Solution

In this post, we are going to solve the Single Number II Leetcode Solution problem of Leetcode. This Leetcode problem is done in many programming languages like C++, Java, and Python.

Problem

Given an integer array nums where every element appears three times except for one, which appears exactly once. Find the single element and return it.

You must implement a solution with a linear runtime complexity and use only constant extra space.

Example 1:

Input: nums = [2,2,3,2]
Output: 3

Example 2:

Input: nums = [0,1,0,1,0,1,99]
Output: 99

Constraints:

• 1 <= nums.length <= 3 * 104
• -231 <= nums[i] <= 231 - 1
• Each element in nums appears exactly three times except for one element which appears once.

Now, let’s see the leetcode solution of Single Number II Leetcode Solution.

Single Number II Leetcode Solution in Python

class Solution:
  def singleNumber(self, nums: List[int]) -> int:
    ones = 0
    twos = 0

    for num in nums:
      ones ^= num & ~twos
      twos ^= num & ~ones

    return ones

Single Number II Leetcode Solution in CPP

class Solution {
 public:
  int singleNumber(vector<int>& nums) {
    int ans = 0;

    for (int i = 0; i < 32; ++i) {
      int sum = 0;
      for (const int num : nums)
        sum += num >> i & 1;
      sum %= 3;
      ans |= sum << i;
    }

    return ans;
  }
};

Single Number II Leetcode Solution in Java

class Solution {
  public int singleNumber(int[] nums) {
    int ans = 0;

    for (int i = 0; i < 32; ++i) {
      int sum = 0;
      for (final int num : nums)
        sum += num >> i & 1;
      sum %= 3;
      ans |= sum << i;
    }

    return ans;
  }
}

Note: This problem Single Number II is generated by Leetcode but the solution is provided by Chase2learn This tutorial is only for Educational and Learning purpose.