[COI2007] Patrik 音樂會的等待 單調棧
阿新 • • 發佈:2018-11-08
Code:
#include<cstdio> #include<algorithm> #include<iostream> #include<cstring> #include<stack> #include<string> using namespace std; void setIO(string a){ freopen((a+".in").c_str(),"r",stdin),freopen((a+".out").c_str(),"w",stdout); } void shutIO(){fclose(stdin),fclose(stdout);} #define maxn 500009 int val[maxn]; struct Node{ int val,h; Node(int val=0,int h=0):val(val),h(h){} }; stack<Node>S; int main(){ //setIO("wait"); int n,a; long long ans=0; scanf("%d",&n); for(int i=1;i<=n;++i) scanf("%d",&val[i]); S.push(Node(1,val[1])); for(int i=2;i<=n;++i){ a=0; while(!S.empty()&&S.top().h<val[i])ans+=S.top().val,S.pop(); if(!S.empty()&&S.top().h==val[i]) a+=S.top().val,S.pop(); ans+=a; ans+=(!S.empty()); S.push(Node(a+1,val[i])); } printf("%lld",ans); //shutIO(); return 0; }