单调栈模板 POJ3250

上次二分st表大法失败以后的又一次尝试233333

封装，封装，封装！！！！！！

#include <bits/stdc++.h>
using namespace std;
#define limit (500000 + 5)//防止溢出
#define INF 0x3f3f3f3f
#define inf 0x3f3f3f3f3f
#define lowbit(i) i&(-i)//一步两步
#define EPS 1e-6
#define FASTIO  ios::sync_with_stdio(false);cin.tie(0);
#define ff(a) printf("%d\n",a );
#define pi(a,b) pair<a,b>
#define rep(i, a, b) for(ll i = a; i <= b ; ++i)
#define per(i, a, b) for(ll i = b ; i >= a  ; --i)
#define MOD 998244353
#define traverse(u) for(int i = head[u]; ~i ; i = edge[i].next)
#define FOPEN freopen("C:\\Users\\tiany\\CLionProjects\\acm_01\\data.txt", "rt", stdin)
#define FOUT freopen("C:\\Users\\tiany\\CLionProjects\\acm_01\\dabiao.txt", "wt", stdout)
#define debug(x) cout<<x<<endl
typedef long long ll;
typedef unsigned long long ull;
inline ll read(){
    ll sign = 1, x = 0;char s = getchar();
    while(s > '9' || s < '0' ){if(s == '-')sign = -1;s = getchar();}
    while(s >= '0' && s <= '9'){x = (x << 3) + (x << 1) + s - '0';s = getchar();}
    return x * sign;
}//快读
void write(ll x){
    if(x < 0) putchar('-'),x = -x;
    if(x / 10) write(x / 10);
    putchar(x % 10 + '0');
}

int n;
int a[limit];
struct m_stack{
    stack<int>s;
    m_stack():s(){}
    int operator[](const int & element){
        for(; !s.empty() && s.top() <=   element; s.pop());
        int ans = s.size();
        s.push(element);
        return ans;
    }
    void clear(){
        while (s.size())s.pop();
    }
}stk;
int main() {
#ifdef LOCAL
    FOPEN;
#endif
    while (cin>>n){
        ll ans = 0;
        stk.clear();
        stk[-INF];
        rep(i ,1,n){
            cin>>a[i];
        }
        rep(i,1,n){
            ans += stk[a[i]];
        }
       cout<<ans<<endl;
    }
    return 0;
}