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[1] Given an array of integers, every element appears twice except for one. Find that single one.[2] Given an array of integers, every element appears three times except for one. Find that single one. (better solution is needed)Note: Your algorithm should have a linear runtime complexity. Could you implement it without using extra memory?
题目中文意思就是说给定一个整数数组，数组中所有元素都出现了两次，只有一个元素只出现了一次，找出这个只出现了一次的元素。
用异或来解决这类问题会非常简单。
代码：
int SingleNumber(int arr[] , int length){ int i , xor; for(xor = 0 , i = 0 ; i < length ; ++i) xor = xor ^ arr[i]; return xor;} 完整代码：
1 #include2 using namespace std; 3 4 int SingleNumber(int arr[] , int length) 5 { 6 int i , xor; 7 for(xor = 0 , i = 0 ; i < length ; ++i) 8 xor = xor ^ arr[i]; 9 10 return xor;11 }12 13 int main()14 {15 int arr[] = { 2 , 1 , 2 , 1 , 3 , 4 , 3};16 int length = sizeof(arr)/ sizeof(int);17 18 cout<
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