不就是这么做的吗@[丹莫刺尔](/space/show?uid=49118)
by λᴉʍ @ 2017-09-27 18:48:05
我甘败下风
```cpp
#include<iostream>
#include<algorithm>
using namespace std;
int a[100000000];
int main(){
int n,i;
cin>>n;
for(i=1;i<=n;i++)
cin>>a[i];
sort(a+1,a+1+n);
for(i=1;i<=n;i+=2)
if(a[i]!=a[i+1])
{
cout<<a[i];
break;
}
return 0;
}
```
by My_Faith @ 2017-09-28 17:11:40
```cpp
#include<iostream>
using namespace std;
int main(){
int n,ans=0;
scanf("%d",&n);
for (int i=1;i<=n;i++){
int a;
scanf("%d",&a);
ans=ans^a;
}
printf("%d",ans);
}
```
by 2016gdgzoi746 @ 2017-09-30 13:48:05
竟然没有MLE！
```
#include<stdio.h>
#define max(a,b) a>b?a:b;
int a[10000001];
int main()
{
int t,n,i,ans=0,flag=0;
scanf("%d",&n);
for(i=0;i<n;i++)
{
scanf("%d",&t);
a[t]++;
ans=max(ans,t);
}
for(i=1;i<=ans;i++)
if(a[i]%2==1)
{
flag=i;
break;
}
printf("%d",flag);
}
```
by TRZ_2007 @ 2018-05-24 20:46:40
#include<iostream>
using namespace std;
long long n,a[100001],k;
int main()
{
cin>>n;
for(int i=1;i<=n;i++)
{
cin>>k;
a[k]++;
}
for(int i=1;;i++)
if(a[i]%2==1)
{
cout<<i;
return 0;
}
}
by 真炎幸魂 @ 2018-07-22 17:25:46
###### 然鹅~~~~TLE!!!
------------------------------------
```
// luogu-judger-enable-o2
#include<bits/stdc++.h>
using namespace std;
int main()
{
int n,l,t=0,ans=0;
cin>>n;
pair<int,bool>a[n];
for(int i=0;i<n;i++)
{
cin>>l;
make_pair(l,false);
}
sort(a,a+n);
while(t!=1)
{
int i=0;
if(a[i].first!=a[i+1].first)
{
t=1;
ans=a[i].first;
}
else while(a[i].first==a[i+1].first)
{
a[i].second=true;
a[i+1].second=true;
i+=2;
}
}
cout<<ans;
return 0;
}
```
by 憨憨憨憨批 @ 2019-02-12 21:49:30