[SDOI2009][bzoj1878] HH的项链 [莫队模板题]

题面：

传送门

思路：

就是一道莫队的模板题目......

开一个1000000的数组记录每个数出现的次数，然后每次从1到0或者从0到1更新答案

莫队讲解看这里：莫队

Code：

 #include<iostream>
 #include<cstdio>
 #include<cstring>
 #include<algorithm>
 #include<cmath>
 using namespace std;
 inline int read(){
     int re=,flag=;char ch=getchar();
     while(ch>''||ch<''){
         if(ch=='-') flag=-;
         ch=getchar();
     }
     while(ch>=''&&ch<='') re=(re<<)+(re<<)+ch-'',ch=getchar();
     return re*flag;
 }
 int n,m,cnt[],tot=,x[],curl,curr,block,ans[];
 struct query{
     int l,r,i;
 }a[];
 bool cmp(query l,query r){
     if(l.l/block!=r.l/block) return (l.l/block)<(r.l/block);
     else return l.r<r.r;
 }
 void add(int i){
     cnt[x[i]]++;if(cnt[x[i]]==) tot++;
     //cout<<"add "<<i<<" "<<x[i]<<" "<<cnt[x[i]]<<"\n";
 }
 void erase(int i){
     cnt[x[i]]--;if(!cnt[x[i]]) tot--;
     //cout<<"erase "<<i<<" "<<x[i]<<" "<<cnt[x[i]]<<"\n";
 }
 int main(){
     //freopen("diff.in","r",stdin);
     //freopen("diff.out","w",stdout);
     int i;
     n=read();for(i=;i<=n;i++) x[i]=read();block=sqrt(n);
     //cout<<"input one complete "<<n<<" "<<i<<"\n";
     m=read();for(i=;i<=m;i++) a[i].l=read(),a[i].r=read(),a[i].i=i;
     //cout<<"input two complete "<<m<<" "<<i<<"\n";
     sort(a+,a+m+,cmp);curl=a[].l;curr=a[].r;
     for(i=a[].l;i<=a[].r;i++) add(i);
     ans[a[].i]=tot;
     for(i=;i<=m;i++){
         while(curl<a[i].l) erase(curl++);
         while(curl>a[i].l) add(--curl);
         while(curr<a[i].r) add(++curr);
         while(curr>a[i].r) erase(curr--);
         ans[a[i].i]=tot;
         //cout<<"now "<<curl<<" "<<curr<<"\n";
     }
     for(i=;i<=m;i++) printf("%d\n",ans[i]);
 }