Commit 3ac9dfe

package leetcodeEasyLevel;

import java.util.Arrays;

import java.util.HashSet;

import java.util.Set;

public class _0136SingleNumber {

public static int singleNumber(int[] nums) {

//sol1 => Runtime 1 ms Memory 47.9 MB

// 비트 연산자(^) : 대응되는 비트가 서로 같으면 0을, 다르면 1을 반환함. (비트 XOR 연산)

// http://www.tcpschool.com/c/c_operator_bitwise

/*

//sol2 => Runtime 10 ms Memory 40 MB

// HashSet : contains()을 통해 있으면 remove, 없으면 add해서 남은

// https://www.w3schools.com/java/java_hashset.asp

Set<Integer> box = new HashSet<>();

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

if (box.contains(nums[i])) {

box.remove(nums[i]);

} else {

box.add(nums[i]);

}

}

return box.stream().findFirst().get();

}

public static void main(String[] args) {

int[] nums =// {2, 2, 1};

//{4,1,2,1,2};

//{1};

//{-1,-1,-2}; //=> -2

//{1,3,1,-1,3};

{-336,513,-560,-481,-174,101,-997,40,-527,-784,-283,-336,513,-560,-481,-174,101,-997,40,-527,-784,-283,354}; //=> 354

System.out.println(singleNumber(nums));

}

}