题解 CF637B

题目大意：

维护个栈，去重保留最上层

题目分析：

啥也不是，数组模拟 \(\text{stack} + \text{unordered\_map}\) 直接秒掉。

复杂度 \(O(n)\)

代码实现：

#include <bits/stdc++.h>
#define debug(x) cerr<<#x<<": "<<x<<endl;
#define int long long
using namespace std;

inline int read()
{
	int x=0,f=1;char ch=getchar();
	while (ch<'0'||ch>'9'){if (ch=='-') f=-1;ch=getchar();}
	while (ch>='0'&&ch<='9'){x=x*10+ch-48;ch=getchar();}
	return x*f;
}

namespace Larry76{
    const int MAX_SIZE = 2e5;
    string sta[MAX_SIZE];
    map<string,bool>hashtable;
    int top = 0;
    void main(){
        //Code Here;
        int n;
        cin>>n;
        string buffer;
        while(n--){
            cin>>buffer;
            sta[++top] = buffer;
        }
        while(top){
            if(!hashtable[sta[top]]){
                cout<<sta[top]<<endl;
                hashtable[sta[top]] = 1;
            }
            --top;
        }
    }
}

signed main(){
#ifdef LOCAL
    freopen("in.in","r",stdin);
    freopen("out.out","w",stdout);
    double c1 = clock();
#else
    ios::sync_with_stdio(false);
#endif
//============================================
    Larry76::main();
//============================================
#ifdef LOCAL
    double c2 = clock();
    cerr<<"Used Time: "<<c2-c1<<"ms"<<endl;
    if(c2-c1>1000)
        cerr<<"Warning!! Time Limit Exceeded!!"<<endl;
    fclose(stdin);
    fclose(stdout);
#endif
    return 0;
}