9D.cpp

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*/                              
#include<bits/stdc++.h>
using namespace std;
 
#define fastio ios_base::sync_with_stdio(0); cin.tie(0)
#define LL long long 
#define mod 1000000007 
#define FOR(i, j, k) for (auto i=j ; i<k ; i++)
#define ROF(i, j, k) for (auto i=j ; i>=k ; i--) 
#define debug(...) fprintf(stderr, __VA_ARGS__), fflush(stderr)
#define time__(d) for(long blockTime = 0; (blockTime == 0 ? (blockTime=clock()) != 0 : false); debug("%s time : %.4fs", d, (double)(clock() - blockTime) / CLOCKS_PER_SEC))

const long long INF = 1e18;
const long long MAX = 1e5+10;
int main(){
    fastio;
    int t=1; cin>>t;
    while(t--){
        int n; cin>>n; int a[n+1],b[5000]={0}; FOR(i,0,n) cin>>a[i],b[a[i]]++;
        vector<int>ans;
        while(1) {
            bool pos = true;
            FOR(j,0,n) if(a[j]!=j) pos = false;
            if(pos) break;
            int mxe;
            FOR(j,0,5000) if(b[j]==0) {mxe=j;  break;}
            if(mxe==n) {
                int k;
                FOR(j,0,n) if(a[j]!=j) { b[a[j]]--; b[n]++; a[j]=n; ans.push_back(j+1);break;}
            }else {
                b[a[mxe]]--; b[mxe]++; a[mxe]=mxe; ans.push_back(mxe+1);  
            }
        }
        cout<<ans.size()<<"\n";
        for(auto i : ans) cout<<i<<" ";   
       // FOR(i,1,n+1) cout<<a[i]<<" ";
        cout<<"\n";
    }
}