数据结构(主席树)：HDU 5654 xiaoxin and his watermelon candy

 1 #include <iostream>
 2 #include <cstring>
 3 #include <cstdio>
 4 #include <algorithm>
 5 using namespace std;
 6 const int maxn=200010;
 7 int a[maxn],Hash[maxn],ok[maxn];
 8 int pre[maxn],nxt[maxn],head[maxn],fa[maxn],son[maxn];
 9 int sum[maxn*30],ch[maxn*30][2],rt[maxn],cnt;
10 void Insert(int pre,int &rt,int l,int r,int g,int d){
11     rt=++cnt;
12     ch[rt][0]=ch[pre][0];
13     ch[rt][1]=ch[pre][1];
14     sum[rt]=sum[pre]+d;
15     if(l==r)return;
16     int mid=(l+r)>>1;
17     if(mid>=g)Insert(ch[pre][0],ch[rt][0],l,mid,g,d);
18     else Insert(ch[pre][1],ch[rt][1],mid+1,r,g,d);
19 }
20 
21 int Query(int rt,int l,int r,int a,int b){
22     if(l>=a&&r<=b)return sum[rt];
23     int mid=(l+r)>>1,ret=0;
24     if(mid>=a)ret=Query(ch[rt][0],l,mid,a,b);
25     if(mid<b)ret+=Query(ch[rt][1],mid+1,r,a,b);
26     return ret;
27 }
28 void Init(){
29     memset(rt,0,sizeof(rt));
30     memset(head,0,sizeof(head));
31     memset(pre,0,sizeof(pre));
32     memset(son,0,sizeof(son));
33     memset(nxt,0,sizeof(nxt));
34     memset(fa,0,sizeof(fa));
35     memset(sum,0,sizeof(sum));
36     memset(ok,0,sizeof(ok));cnt=0;
37 }
38 int main(){
39     int T,Q,n,l,r;a[0]=-1;
40     scanf("%d",&T);
41     while(T--){
42         Init();
43         scanf("%d",&n);
44         for(int i=1;i<=n;i++)
45             scanf("%d",&a[i]);
46         for(int i=1;i<=n;i++)
47             Hash[i]=a[i];
48         sort(Hash+1,Hash+n+1);
49         for(int i=1;i<=n;i++)
50             a[i]=lower_bound(Hash+1,Hash+n+1,a[i])-Hash;
51         for(int i=2;i<n;i++)
52             if(a[i-1]<=a[i]&&a[i]<=a[i+1])
53                 ok[i]=1;
54         for(int i=1;i<=n;i++){
55             pre[i]=head[a[i]];
56             nxt[pre[i]]=i;
57             head[a[i]]=i;
58         }
59         for(int i=2;i<n;i++)
60             if(ok[i]){
61                 int j=pre[i];
62                 while(j&&(a[j-1]!=a[i-1]||a[j+1]!=a[i+1])){j=pre[j];}
63                 fa[i]=j;son[j]=i;
64             }
65         for(int i=2;i<n;i++){
66             if(!fa[i]&&ok[i])    
67                 Insert(rt[1],rt[1],1,n,i,1);    
68         }
69         
70         for(int i=2;i<n;i++){
71             if(!ok[i]){
72                 rt[i]=rt[i-1];
73                 continue;
74             }
75             Insert(rt[i-1],rt[i],1,n,i,-1);    
76             if(son[i])Insert(rt[i],rt[i],1,n,son[i],1);
77         }
78         scanf("%d",&Q);
79         while(Q--){
80             scanf("%d%d",&l,&r);
81             printf("%d\n",r-1>=l?Query(rt[l],1,n,1,r-1):0);
82         }
83     }
84     return 0;
85 }