按照题意模拟即可

核心代码:

while(n--){
        bool find=false;
        scanf("%d",&k);
        for(int i=L;i<R;i++) if(que[i]==k) find=true;
        if(!find) cnt++,que[R++]=k;
        if(R-L>m) L++; 
    }

循环队列

for(int i = 0;i < n;++i){
        int tmp;
        scanf("%d", &tmp);
        if(hash[tmp])   continue;
        hash[tmp] = 1;
        if(head == tail && i )    hash[zhan[tail]] = 0,tail = (tail + 1) % m;  //删除标记。出队
        zhan[head] = tmp, head = (head + 1) % m;   //入队