bzoj1657[Usaco2006 Mar]Mooo 奶牛的歌声*

 1 #include <cstdio>
 2 #include <cstring>
 3 #include <algorithm>
 4 #define inc(i,j,k) for(int i=j;i<=k;i++)
 5 #define dec(i,j,k) for(int i=j;i>=k;i--)
 6 #define maxn 50100
 7 using namespace std;
 8 
 9 int s1[maxn],s2[maxn],h[maxn],vol[maxn],ss,n,ans[maxn];
10 inline int read(){
11     char ch=getchar(); int f=1,x=0;
12     while(ch<‘0‘||ch>‘9‘){if(ch==‘-‘)f=-1; ch=getchar();}
13     while(ch>=‘0‘&&ch<=‘9‘)x=x*10+ch-‘0‘,ch=getchar();
14     return f*x;
15 }
16 int main(){
17     n=read(); inc(i,1,n)h[i]=read(),vol[i]=read();
18     s1[1]=h[1]; s2[1]=1; ss=1;
19     inc(i,2,n){while(ss&&s1[ss]<h[i])ss--; if(ss)ans[s2[ss]]+=vol[i]; s1[++ss]=h[i]; s2[ss]=i;}
20     s1[1]=h[n]; s2[1]=n; ss=1;
21     dec(i,n-1,1){while(ss&&s1[ss]<h[i])ss--; if(ss)ans[s2[ss]]+=vol[i]; s1[++ss]=h[i]; s2[ss]=i;}
22     inc(i,1,n)ans[0]=max(ans[0],ans[i]); printf("%d",ans[0]); return 0;
23 }