题解 | 不重复数字

#include <bits/stdc++.h>
using ll = long long ; 
using namespace std;
#define endl '\n'
#define pb push_back
#define ull unsigned long long
#define all(a) a.begin(), a.end()
#define vi vector<ll>
#define vii vector<vector<ll>>
#define fi first 
#define se second
#define vs vector<string>
#define eb emplace_back
#define in insert
#define pf push_front
#define ios ios::sync_with_stdio(false);cin.tie(0);cout.tie(0);
#define rep(i, n) for (ll i = 0; i < (n); ++i)
#define rep1(i, n) for (ll i = 1; i <= (n); i++)
const ll inf = 2e18 + 9 ;
const ll mod1 = 1e9 + 7 ; 
const ll mod2 = 998244353 ; 
typedef pair<int, int> pll;
typedef long double db;
inline ll comb(int n, int k){if (k < 0 || k > n)return 0;if (k == 0 || k == n)return 1;k = min(k, n - k);ll numerator = 1;  ll denominator = 1; for (int i = 1; i <= k; ++i){numerator *= (n - k + i);denominator *= i;ll g = __gcd(numerator, denominator);numerator /= g;denominator /= g;}return numerator / denominator;}
void init()
{

}
inline ll gcd(ll a , ll b) {return b ? gcd(b , a % b) : a;};
inline int read(){int x = 0;short f = 1;char c = getchar();while ((c < '0' || c > '9') && c != '-')c = getchar();if (c == '-')f = -1, c = getchar();while (c >= '0' && c <= '9')x = x * 10 + c - '0', c = getchar();x *= f;return x;}
inline ll qsm(ll a , ll b){ll res = 1 ; while(b){if(b & 1){res *= a ; }b >>= 1 ; a *= a ; }return res ; }
int dir[4][2] = {{1 , 0} , {-1 , 0} , {0 , 1} , {0 , -1}};
int dirx[8] = {-1, -1, -1, 0, 0, 1, 1, 1}; 
int diry[8] = {-1, 0, 1, -1, 1, -1, 0, 1};
void work() 
{
    int n ; cin >> n ;
    vi b ;
    vi a(n + 1) ;  
    unordered_map<int , int>mp ;  
    for(int i = 1 ; i <= n ; i++)
    {
        int x ; cin >> x;
        a[i] = x ; 
        if(mp[x] == 0)
        {
            mp[x] = i ; 
        } 
    }
    for(int i = 1 ; i <= n ; i++)
    {
        if(mp[a[i]] >= i)
        {
            b.pb(a[i]) ; 
        }
    }
    for(int i = 0 ; i < b.size() ; i++)
    {
        cout << b[i] << " " ; 
    }
    cout << endl ;
}
signed main() 
{
    init() ;
    ios ;
    int t = 1;
    cin >> t ; 
    while (t--) 
    {
        work();
    }
    return 0;
}