BZOJ 4408 主席数+找规律

 1 #include <cstdio>
 2 const int Maxn=100010;
 3 inline void Get_Int(int &x)
 4 {
 5     char ch=getchar(); x=0;
 6     while (ch<‘0‘ || ch>‘9‘) ch=getchar();
 7     while (ch>=‘0‘ && ch<=‘9‘) {x=x*10+ch-‘0‘; ch=getchar();}
 8 }
 9 struct Node
10 {
11     Node * l,* r; int Sum;
12     inline void Push_Up() {Sum=l->Sum+r->Sum;}
13 };
14 Node Memory[Maxn*100],* port=Memory,* null,* Root[Maxn];
15 int n,m,Mx,a[Maxn],l,r;
16 inline int Max(int x,int y) {return x>y?x:y;}
17 inline void Init() {null=port++; null->Sum=0; null->l=null->r=null;}
18 inline Node * NewNode(Node * x)
19 {
20     Node * Ret=port++;
21     if (x==null) {Ret->l=Ret->r=null; Ret->Sum=0;} else
22         {Ret->l=x->l,Ret->r=x->r,Ret->Sum=x->Sum;}
23     return Ret;
24 }
25
26 Node * Insert(Node * Pre,int o,int l,int r,int v)
27 {
28     Node * Ret=NewNode(Pre);
29     if (l==r)
30     {
31         Ret->Sum+=v;
32         return Ret;
33     }
34     int mid=(l+r)>>1;
35     if (v<=mid) Ret->l=Insert(Pre->l,o<<1,l,mid,v); else Ret->r=Insert(Pre->r,o<<1|1,mid+1,r,v);
36     Ret->Push_Up();
37 }
38 int Sum(Node * Now,int o,int l,int r,int p,int q)
39 {
40     if (Now==null) return 0;
41     if (l==p && r<=q) return Now->Sum;
42     int mid=(l+r)>>1;
43     if (q<=mid) return Sum(Now->l,o<<1,l,mid,p,q);
44     if (p>=mid+1) return Sum(Now->r,o<<1|1,mid+1,r,p,q);
45     if (p<=mid && q>=mid+1) return Sum(Now->l,o<<1,l,mid,p,mid)+Sum(Now->r,o<<1|1,mid+1,r,mid+1,q);
46 }
47 inline int Query(int L,int R)
48 {
49     int Ret=1;
50     while (true)
51     {
52         int t=Sum(Root[R],1,1,Mx,1,Ret)-Sum(Root[L],1,1,Mx,1,Ret);
53         if (t<Ret) return Ret; else Ret=t+1;
54     }
55     return Ret;
56 }
57 int main()
58 {
59     // freopen("data.in","r",stdin);
60     // freopen("data.out","w",stdout);
61     Init();
62     Get_Int(n);
63     for (int i=1;i<=n;i++) Get_Int(a[i]),Mx=Max(Mx,a[i]);
64     Root[0]=NewNode(null);
65     for (int i=1;i<=n;i++) Root[i]=Insert(Root[i-1],1,1,Mx,a[i]);
66     Get_Int(m);
67     for (int i=1;i<=m;i++)
68     {
69         Get_Int(l),Get_Int(r);
70         printf("%d\n",Query(l-1,r));
71     }
72     return 0;
73 }

C++

网上题解一堆..即找到1~Mx.那么1~Mx的Sum就都可以取到.

BZOJ上问Root讨来数据自测全A，交上去WA.