Luogu3952 NOIP2017时间复杂度

　　搞一个栈模拟即可。对比一下和一年前考场上的代码233

//2018.11.8
#include<iostream>
#include<cstdio>
#include<cmath>
#include<cstdlib>
#include<cstring>
#include<algorithm>
using namespace std;
#define N 110
char getc(){char c=getchar();while ((c<'A'||c>'Z')&&(c<'a'||c>'z')&&(c<''||c>'')) c=getchar();return c;}
int read()
{
    int x=,f=;char c=getchar();
    while (c<''||c>'') {if (c=='-') f=-;c=getchar();}
    while (c>=''&&c<='') x=(x<<)+(x<<)+(c^),c=getchar();
    return x*f;
}
int getlim()
{
    char c=getc();
    if (c=='n') return ;
    else
    {
        int l=c^,c=getchar();
        if (c>=''&&c<='') l=l*+(c^);
        return l;
    }
}
int T,top;
bool isenter[N],isconst[N],isappear[];
char var[N];
int main()
{
    T=read();
    while (T--)
    {
        memset(isappear,,sizeof(isappear));top=;
        int n=read();getc();
        char c=getc();int p;
        if (c=='') p=;else p=read();
        bool iserr=;int cnt=,ans=,isout=;
        while (n--)
        {
            c=getc();
            if (c=='F')
            {
                char v=getc();
                if (isappear[v]) iserr=;
                int l=getlim(),r=getlim();
                if (!iserr)
                {
                    var[++top]=v;isappear[v]=;
                    isconst[top]=r-l<=;
                    isenter[top]=r>=l;
                    if (!isout) ans=max(ans,cnt+=isconst[top]^);
                    isout+=isenter[top]^;
                }
            }
            else
            {
                if (top==) iserr=;
                if (!iserr)
                {
                    isout-=isenter[top]^;
                    if (!isout) cnt-=isconst[top]^;
                    isappear[var[top]]=;
                    top--;
                }
            }
        }
        if (top!=) iserr=;
        if (iserr) cout<<"ERR"<<endl;
        else if (ans==p) cout<<"Yes"<<endl;
        else cout<<"No"<<endl;
    }
    return ;
}

//2017.11.11
#include<iostream>
#include<cstdio>
#include<cstdlib>
#include<cstring>
#include<cmath>
#include<algorithm>
using namespace std;
int t,n,w,top;
bool flag=,a[],ifn[],ifcmp[];
char stk[];
int main()
{
    cin>>t;
    while (t>)
    {
        t--;
        cin>>n;
        char c=getchar();
        while ((c<''||c>'')&&(c!='n')) c=getchar();
        //cout<<c<<endl;
        if (c=='') w=;
        else
        {
            c=getchar();
            cin>>w;
        }
        //cout<<w<<endl;
        c=getchar();
        top=;
        memset(a,,sizeof(a));
        memset(ifcmp,,sizeof(ifcmp));
        flag=;
        int o=,MAX=,iflr=;
        for (int i=;i<=n;i++)
        {
            c=getchar();while (c!='E'&&c!='F') c=getchar();
            if (c=='E')
            {
                if (top<=) flag=;
                else
                {
                    a[stk[top]]=;
                    if (ifn[top]) o--;
                    if (ifcmp[top]) iflr--;
                    top--;
                }
            }
            else
            {
                char x;int l,r;
                cin>>x;char tmp=x;
                if (a[x]) flag=;
                else
                {
                    a[x]=;
                    cin>>x;
                    if (x=='n') l=;
                    else
                    {
                        l=x-;
                        x=getchar();
                        if (x>=''&&x<='') l=l*+x-;
                    }
                    cin>>x;
                    if (x=='n') r=;
                    else
                    {
                        r=x-;
                        x=getchar();
                        if (x>=''&&x<='') r=r*+x-;
                    }
                    if (l>r)
                    {
                        top++;
                        stk[top]=tmp;
                        ifn[top]=;
                        ifcmp[top]=;
                        iflr++;
                    }
                    else if(l<&&r<||l==r)
                    {
                        top++;
                        stk[top]=tmp;
                        ifn[top]=;
                        ifcmp[top]=;
                    }
                    else
                    {
                        top++;
                        stk[top]=tmp;
                        if (iflr) ifn[top]=;
                        else
                        {
                            ifn[top]=;
                            o++;
                            if (o>MAX) MAX=o;
                        }
                        ifcmp[top]=;
                    }
                }
            }
        }
        if (top>) flag=;
        if (!flag) cout<<"ERR"<<endl;
        else
        {
            if (MAX==w) cout<<"Yes"<<endl;
            else cout<<"No"<<endl;
        }
    }
    return ;
}