题解 | 会话列表

#include <iostream>
#include <map>
using namespace std;

int main() {
    int a, b;
    int totalCase = 0;
    cin >> totalCase;
    while (totalCase--) { // 注意 while 处理多个 case
        int count = 0;
        cin >> count;
        int arr[count];
        int res[count];
std:
        map<int, bool> flags;

        for (int k = 0; k < count; k++) {
            cin >> arr[k];
        }

        int resId = 0;
        for (int k = count - 1; k >= 0; k--) {
            if (flags.find(arr[k]) == flags.end()) {
                res[resId] = arr[k];
                flags[arr[k]] = true;
                resId++;
            }
        }
        cout << res[0];
        for (int i = 1 ; i < resId; i ++) {
            cout << ' ' << res[i];
        }
        cout << endl;
    }
}
// 64 位输出请用 printf("%lld")