[POI2014]KUR-Couriers 題目描述 Byteasar works for the BAJ company, which sells computer games. The BAJ company cooperates with many courier companies that ...
[POI2014]KUR-Couriers
題目描述
Byteasar works for the BAJ company, which sells computer games.
The BAJ company cooperates with many courier companies that deliver the games sold by the BAJ company to its customers.
Byteasar is inspecting the cooperation of the BAJ company with the couriers.
He has a log of successive packages with the courier company that made the delivery specified for each package.
He wants to make sure that no courier company had an unfair advantage over the others.
If a given courier company delivered more than half of all packages sent in some period of time, we say that it dominated in that period.
Byteasar wants to find out which courier companies dominated in certain periods of time, if any.
Help Byteasar out!
Write a program that determines a dominating courier company or that there was none.
給一個數列，每次詢問一個區間內有沒有一個數出現次數超過一半
輸入輸出格式
輸入格式：
The first line of the standard input contains two integers, 
and 
(
), separated by a single space, that are the number of packages shipped by the BAJ company and the number of time periods for which the dominating courier is to be determined, respectively.
The courier companies are numbered from 
to (at most) 
.
The second line of input contains 
integers, 
(
), separated by single spaces; 
is the number of the courier company that delivered the 
-th package (in shipment chronology).
The 
lines that follow specify the time period queries, one per line.
Each query is specified by two integers, 
and 
(
), separated by a single space.
These mean that the courier company dominating in the period between the shipments of the 
-th and the 
-th package, including those, is to be determined.
In tests worth 
of total score, the condition 
holds, and in tests worth 
of total score 
.
輸出格式：
The answers to successive queries should be printed to the standard output, one per line.
(Thus a total of 
lines should be printed.) Each line should hold a single integer: the number of the courier company that dominated in the corresponding time period, or 
if there was no such company.
輸入輸出樣例
輸入樣例#1：7 5 1 1 3 2 3 4 3 1 3 1 4 3 7 1 7 6 6輸出樣例#1：
1 0 3 0 4
說明
給一個數列，每次詢問一個區間內有沒有一個數出現次數超過一半
題解：
就是一個主席樹模板。。
1 #include<bits/stdc++.h> 2 using namespace std; 3 4 const int maxn=5e5+5; 5 6 struct node{ 7 int sum,l,r; 8 }t[maxn*21]; 9 int n,m,root[maxn],cnt=1; 10 11 void bt(int &now,int x,int l,int r) 12 { 13 t[cnt++]=t[now]; 14 now=cnt-1; 15 t[now].sum++; 16 if(l==r) 17 return ; 18 int mid=(l+r)>>1; 19 if(x<=mid) 20 bt(t[now].l,x,l,mid); 21 else 22 bt(t[now].r,x,mid+1,r); 23 } 24 25 int query(int i,int j,int x,int l,int r) 26 { 27 if(l==r) 28 return l; 29 int mid=(l+r)>>1; 30 if(2*(t[t[j].l].sum-t[t[i].l].sum)>x) 31 return query(t[i].l,t[j].l,x,l,mid); 32 if(2*(t[t[j].r].sum-t[t[i].r].sum)>x) 33 return query(t[i].r,t[j].r,x,mid+1,r); 34 return 0; 35 } 36 37 int main() 38 { 39 scanf("%d%d",&n,&m); 40 root[0]=0; 41 for(int i=1;i<=n;i++) 42 { 43 int x; 44 scanf("%d",&x); 45 root[i]=root[i-1]; 46 bt(root[i],x,1,n); 47 } 48 for(int i=1;i<=m;i++) 49 { 50 int l,r; 51 scanf("%d%d",&l,&r); 52 printf("%d\n",query(root[l-1],root[r],r-l+1,1,n)); 53 } 54 return 0; 55 }
