LeetCode 136 — Single Number（C++ Java Python）

题目：http://oj.leetcode.com/problems/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?
题目翻译：

给定一个整数数组，除了一个元素，每个元素都出现了两次。找出那个仅出现一次的元素。

注意：

算法应具有线性时间复杂性。你可以不使用额外的内存实现它吗？

分析：

        通过异化来实现。
C++实现：

class Solution {
public:
int singleNumber(int A[], int n) {
// Note: The Solution object is instantiated only once and is reused by each test case.
int result = 0;
for(int i = 0; i < n; ++i)
{
result ^= A[i];
}
return result;
}
};

Java实现：

public class Solution {
public int singleNumber(int[] A) {
// Note: The Solution object is instantiated only once and is reused by each test case.
int result = 0;

for(int num : A) {
result ^= num;
}

return result;
}
}

Python实现：

class Solution:
# @param A, a list of integer
# @return an integer
def singleNumber(self, A):
result = 0

for num in A:
result ^= num

return result

        感谢阅读！