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Algorithm/Leet Code

LeetCode #136 SingleNumber. Algorithm,알고리즘,LeetCode,Codefights,CodeSignal,코드파이트,코드시그널,예제,문제해결능력,example,c++,java,재귀,recursive,datastructure,techinterview,coding,코딩인터뷰,기술면접

LeetCode #136 SingleNumber. Algorithm,알고리즘,LeetCode,Codefights,CodeSignal,코드파이트,코드시그널,예제,문제해결능력,example,c++,java,재귀,recursive,datastructure,techinterview,coding,코딩인터뷰,기술면접





 3종류로 풀었는데 퍼포먼스가 중간 정도밖에 안나오길래 다른사람들 것을 봤더니 xor 를 이용해서 풀었다.

간단한데 xor 관련 연산자들이 2진수 연산인걸 몰랐음. 좀 더 봐야겠다.


xor >>>>>> sort >>> map >>>>>>>>>>>>>> iteration twice   의 순서로 퍼포먼스가 나왔다.




 I solved it with 3 different solution, but max performance was just half of others. So I saw others and re-try with xor operation.

It was simple, but i didn't know that xor operation is about binary. I should study more about it.



performance was..


xor >>>>>> sort >>> map >>>>>>>>>>>>>> iteration twice


 



LeetCode #136

Q.

 Given a non-empty 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?



 비어있지 않은 정수 배열에서, 모든 값들은 두번씩 나오고, 한개만 한번 나온다. 그 한개 값을 찾아라.


 노트 :

선형의 런타임 시간복잡도를 가져야 한다. 추가 메모리 사용없이 구현 가능한가?




e.g. 

Example 1:

Input: [2,2,1]
Output: 1

Example 2:

Input: [4,1,2,1,2]
Output: 4




Process

// Process

//1. Input integer array

//2. Iterate from begin to the end

// 2.1. Check if it has same number

//3. Return single number



// 처리과정

//1. 정수배열 입력받는다.

//2. 시작부터 끝까지 반복한다.

// 2.1. 같은 수가 있는지 확인한다.

//3. 한개인 수를 반환한다.




Code.. lemme see example code!!!

코드.. 예제코드를 보자!!!





#include <iostream>

#include <string>

#include <vector>

#include <map>

#include <algorithm>


using namespace std;



class Solution {

public:


int singleNumber(vector<int>& nums) {


int num = 0;

for (int i = 0; i < nums.size(); ++i) {

num = num ^ nums[i];

}

return num;

}


//int singleNumber(vector<int>& nums) {


// if (nums.size() == 1)

// return nums[0];


// sort(nums.begin(), nums.end());


// for (int i = 0; i < nums.size() - 2; i += 2)

// {

// if (nums[i] != nums[i + 1])

// {

// return nums[i];

// }

// }

// return nums[nums.size()-1];

//}


//int singleNumber(vector<int>& nums) {


// bool hasSame;

// for (int i = 0; i < nums.size(); ++i)

// {

// hasSame = false;

// int j = i+1;

// while (!hasSame && j < nums.size())

// {

// if (nums[i] == nums[j])

// {

// hasSame = true;

// nums.erase(nums.begin() + j);

// }

// ++j;

// }

// if (!hasSame)

// return nums[i];

// }

// return 0;

//}


//int singleNumber(vector<int>& nums) {


// map<int, int> tempMap;


// for (int i = 0; i < nums.size(); ++i)

// {

// auto search = tempMap.find(nums[i]);

// if (search != tempMap.end()) {

// tempMap.erase(nums[i]);

// }

// else 

// {

// tempMap.insert(pair<int, int>(nums[i], nums[i]));

// }

// }

// return tempMap.begin()->first;

//}

};



int main(int argc, char *argv[]) {


//cout << "Hell" << endl;

vector<int> input; // 2 4 4 2 3 5 3

input.push_back(2);

input.push_back(2);

input.push_back(3);

input.push_back(5);

input.push_back(3);


Solution sln;

cout << sln.singleNumber(input) << endl;



}





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