LeetCode之Single Number II

http://oj.leetcode.com/problems/single-number-ii/

找出非重复数字，注意 Every element appears three times
except for one。

需要注意的特殊情况是 n == 1的情况，此情况下不能进行A[i], A[i+1],A[i+2]的比较

class Solution {
public:
int singleNumber(int A[], int n) {
sort(A,A+n);
for(int i = 0; i < n;) {
if(i+1 >= n) return A[i];
if(A[i] != A[i+1] || A[i] != A[i+2]) {
return chooseDiff(A[i], A[i+1],A[i+2]);
}
i += 3;
}
}

int chooseDiff(int a, int b, int c) {
if(a==b) return c;
if(b==c) return a;
if(a==c) return b;
}
};