LintCode 82. 落单的数

LintCode 82. 落单的数

问题描述

问题分析

代码

class Solution {
public:
/*
* @param A: An integer array
* @return: An integer
*/
int singleNumber(vector<int> &A) {
// write your code here
for (int i = 0; i < A.size(); i++) {
if (count(A,A[i]) == 1) {
return A[i];
}
}
}
int count(vector<int> &A,int num) {
int count = 0;
for(int i = 0; i < A.size(); i++) {
if (A[i] == num)
count++;
}
return count;
}
};

代码改进

class Solution {
public:
/*
* @param A: An integer array
* @return: An integer
*/
int singleNumber(vector<int> A) {
int ans = 0;
for(int i=0; i<A.size(); ++i)
ans ^= A[i];
return ans;
}
};