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| #include<bits/stdc++.h> #define pt putchar(' ') #define nl puts("") #define pi pair<int,int> #define pb push_back #define go(it) for(auto &it:as[x]) using namespace std;
const int N=1e6+10; int n; int a[N]; char c[N];
int fr(){ int x=0,flag=1; char ch=getchar(); while(ch<'0' || ch>'9'){ if(ch=='-') flag=-1; ch=getchar(); } while(ch>='0' && ch<='9'){ x=x*10+(ch-'0'); ch=getchar(); } return x*flag; } void fw(int x){ if(x<0) putchar('-'),x=-x; if(x>9) fw(x/10); putchar(x%10+'0'); } int max(int a,int b){return a>b?a:b;} int min(int a,int b){return a<b?a:b;}
bool check(int l1,int r1,int l2,int r2) { int idx=1; while(idx<n/2) { if(l1<r1 && a[l1]==a[r1]) { l1++,r1--; c[++idx]='L',c[n-idx+1]='L'; } else if(l1<=r1 && l2<=r2 && a[l1]==a[l2]) { l1++,l2++; c[++idx]='L',c[n-idx+1]='R'; } else if(l1<=r1 && l2<=r2 && a[r1]==a[r2]) { r1--,r2--; c[++idx]='R',c[n-idx+1]='L'; } else if(l2<r2 && a[l2]==a[r2]) { l2++,r2--; c[++idx]='R',c[n-idx+1]='R'; } else return 0; } return 1; }
void solve() { memset(c,0,sizeof c); n=fr()<<1; for(int i=1;i<=n;i++) a[i]=fr(); int p=2; while(a[p]!=a[1]) p++; c[1]=c[n]='L'; if(check(2,p-1,p+1,n)) {printf("%s\n",c+1);return;} p=n-1; while(a[p]!=a[n]) p--; c[1]='R',c[n]='L'; if(check(1,p-1,p+1,n-1)) {printf("%s\n",c+1);return;} puts("-1"); }
int main() { int T=fr(); while(T--) solve();
return 0; }
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