PAT (Advanced Level) Practice - 1057 Stack（30 分）

#include<bits/stdc++.h>#include<cmath>#define mem(a,b) memset(a,b,sizeof a)#define ssclr(ss) ss.clear(), ss.str("")#define INF 0x3f3f3f3f#define MOD 1000000007usingnamespacestd;
typedeflonglongll;
stack<int>sk;
multiset<int>stmax; // 0->1multiset<int,greater<int>>stmin; // 1->0intmid;
voidkeep()
{
intlen1=stmin.size(), len2=stmax.size();
if(len1<len2) // 1 2    {
stmin.insert(*stmax.begin());
stmax.erase(stmax.begin());
    }
elseif(len1-len2>=2) // 2 2，5 3    {
stmax.insert(*stmin.begin());
stmin.erase(stmin.begin());
    }
mid=*stmin.begin();
}
intmain()
{
intn,val,id;
charop[15];
scanf("%d",&n);
for(inti=0;i<n;i++)
    {
scanf("%s",op);
if(op[1]=='u')
        {
scanf("%d",&val);
sk.push(val);
if(val<=mid) stmin.insert(val);
elsestmax.insert(val);
keep();
        }
elseif(op[1]=='o')
        {
if(sk.size()==0) puts("Invalid");
else            {
inttp=sk.top(); sk.pop();
printf("%d\n",tp);
if(tp>*stmin.begin()) stmax.erase(stmax.find(tp));
elsestmin.erase(stmin.find(tp));
if(sk.size()!=0) keep();
            }
        }
elseif(op[1]=='e')
        {
if(sk.size()==0) puts("Invalid");
elseprintf("%d\n",mid);
        }
    }
return0;
}