题目： 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? **************************我是分割线*********************************
class Solution { public: int singleNumber(vector<int>& nums) { multimap<int,int> coun; for(int i=0;i<nums.size();i++) { coun.insert({nums[i],i}); } int j=0; for(;j<nums.size();j++) { if(coun.count(nums[j])==1) break; } return nums[j]; } }; //测试程序 int main() { int array[]={1,2,3,4,5,4,3,2,1}; Solution c; vector<int > ve(array,array+9); int resu; resu=c.singleNumber(ve); cout<<resu<<endl; return 0; }