POJ 3250 Bad Hair Day（单调栈）

#include <iostream>
#include <cstdio>
#include <cstring>
#include <algorithm>
#include <cstring>
using namespace std;
#define LL long long
int N;
int q[80005];
int top;
int main(){
    scanf("%d",&N);
    top=0;
    int cur;
    LL res=0;
    for(int i=0;i<N;i++){
        scanf("%d",&cur);
        while(top&&q[top]<=cur){
            top--;
        }
        res+=top;
        q[++top]=cur;
    }
    printf("%I64d\n",res);
    return 0;
}