看到题解里有dalao离散化写得很妙，于是用这个思路写了一发：

#include<iostream>
#include<cstdio>
#include<cstring>
#include<algorithm>
#include<queue>
#define ll long long
using namespace std;
inline ll read()
{
    ll x=0,f=1;char ch=getchar();
    while(ch<'0'||ch>'9')
	{
        if(ch=='-')f=-1;
        ch=getchar();
    }
    while(ch>='0'&&ch<='9')
    x=x*10+ch-'0',ch=getchar();
    return x*f;
}
struct num
{
	int wz;
	bool flag;
	ll w;
}a[50005];
bool cmp1(num x,num y){return x.w<y.w;/*if(x.w==y.w)return x.wz<y.wz;*/}
bool cmp2(num x,num y){return x.wz<y.wz;}
int t,n,l;
int main()
{
	t=read();
	while(t--)
	{
		n=read();
		for(int i=1;i<=n;i++)
		{
			a[i].w=read();
			a[i].wz=i;
			a[i].flag=0;
		}
		sort(a+1,a+1+n,cmp1);
		for(int i=1;i<=n;i+=l)
		{
			l=1;
			for(int j=i+1;j<=n;j++)
			{
				if(a[i].w==a[j].w)a[j].flag=1,l++;
				else break;
			}
		}
		sort(a+1,a+1+n,cmp2);
		for(int i=1;i<=n;i++)
		if(!a[i].flag)printf("%lld ",a[i].w);
		printf("\n");
	}
	return 0;
}

然后全WA了，接下来我改了又改，几乎要和题解一模一样了：

#include<iostream>
#include<cstdio>
#include<cstring>
#include<algorithm>
#include<queue>
#define ll long long
using namespace std;
inline int read()
{
    int x=0,f=1;char ch=getchar();
    while(ch<'0'||ch>'9')
	{
        if(ch=='-')f=-1;
        ch=getchar();
    }
    while(ch>='0'&&ch<='9')
    x=x*10+ch-'0',ch=getchar();
    return x*f;
}
struct num
{
	int wz,w;
}a[50005];
bool cmp1(num x,num y){return x.w>y.w;if(x.w==y.w)return x.wz<y.wz;}
bool cmp2(num x,num y){return x.wz<y.wz;}
int t,n,l;
int main()
{
	t=read();
	while(t--)
	{
		scanf("%d",&n);
		for(int i=1;i<=n;i++)
		{
			a[i].w=read();
			a[i].wz=i;
		}
		sort(a+1,a+1+n,cmp1);
		for(int i=1;i<=n;i+=l)
		{
			l=1;
			for(int j=i+1;j<=n;j++)
			{
				if(a[i].w==a[j].w)a[j].w=-2147483649,l++;
				else break;
			}
		}
		sort(a+1,a+1+n,cmp2);
		for(int i=1;i<=n;i++)
		if(a[i].w!=-2147483649)printf("%lld ",a[i].w);
		printf("\n");
	}
	return 0;
}

然而还是WA了，不明白啊……