[了解一下](https://www.luogu.org/discuss/show?postid=11410)
by lolte @ 2018-07-22 10:19:08
但不会用
by ylxmf2020 @ 2018-07-22 10:20:34
哪位dalao的小号
by ylxmf2020 @ 2018-07-22 10:20:54
```cpp
for(int i(2);i<=n;++i){
printf("%d %d\n",i,rand()%(i-1)+1);
}
```
by ygsldr @ 2018-07-22 10:23:22
```cpp
#include <bits/stdc++.h>
#define N 1000000+110
using namespace std;
int n,a[N];
int main()
{
freopen("data.out","w",stdout);
srand((unsigned)time(NULL));
n=1+rand()%1000000;
printf("%d\n",n);
for(register int i=1;i<=n;i++)
a[i]=i;
swap(a[1],a[n]);
for(register int i=1;i<n;i++)
{
int v=1+rand()%(n-i),u=n-i+1+rand()%i;
printf("%d %d\n",a[u],a[v]);
swap(a[v],a[n-i]);
}
return 0;
}
```
大概就这样吧QwQ
by DimensionTripper @ 2018-07-22 10:32:41