poj 3250 Bad Hair Day 栈的简单运用

#include<iostream>
usingnamespacestd;
#include<stack>
typedeflonglongll;
lla[100000];
intmain()
{
stack<ll>s;
intn;
while(cin>>n)
{
for(inti=1;i<=n;i++)
scanf("%d",&a[i]);
s.push(a[1]);
llnum=1;
llsum=0;
for(inti=2;i<=n;i++)
{
while(!s.empty()&&a[i]>=s.top())
{
s.pop();
num--;
}
sum+=num;
num++;
s.push(a[i]);

}
while(!s.empty())
s.pop();
cout<<sum<<endl;
}
return0;
}