D-query

SPOJ - DQUERY

题意 求区间内出现一共有几种数字。

上次写了一个主席树，这次用一下莫队，莫队是离线询问的一种操作，将询问分块，如果在同一个块内就按照右端点排序，如果不在同一个块内就按照块的位置大小排序。

代码：

 #include<bits/stdc++.h>
 using namespace std;
 #define Fopen freopen("_in.txt","r",stdin); freopen("_out.txt","w",stdout);
 #define LL long long
 #define ULL unsigned LL
 #define fi first
 #define se second
 #define pb push_back
 #define lson l,m,rt<<1
 #define rson m+1,r,rt<<1|1
 #define max3(a,b,c) max(a,max(b,c))
 #define min3(a,b,c) min(a,min(b,c))
 #define _S(X) cout << x << ' ';
 #define __S(x) cout << x << endl;
 typedef pair<int,int> pll;
 const int INF = 0x3f3f3f3f;
 const LL mod =  (int)1e9+;
 const int N = 2e5 + ;
 int cnt[N*];
 int a[N*];
 int ans;
 int m;
 int Ans[N];
 struct Node{
     int l, r, id;
 }q[N];

 inline void Add(int p){
     cnt[a[p]]++;
     if(cnt[a[p]] == ) ans++;
 }
 inline void Remove(int p){
     cnt[a[p]]--;
     if(!cnt[a[p]]) ans--;
 }
 inline bool cmp(Node x1, Node x2){
     if(x1.l/m != x2.l/m){
         return x1.l/m < x2.l/m;
     }
     return x1.r < x2.r;
 }
 int main(){
     int n;
     scanf("%d", &n);
     m = sqrt(n);
     for(int i = ; i <= n; i++)
         scanf("%d", &a[i]);
     int p;
     scanf("%d", &p);
     for(int i = ; i <= p; i++){
         scanf("%d%d", &q[i].l, &q[i].r);
         q[i].id = i;
     }
     sort(q+, q++p, cmp);
     int L = , R = ;
     for(int i = ; i <= p; i++){
         int tL = q[i].l, tR = q[i].r;
         while(L < tL) Remove(L++);
         while(L > tL) Add(--L);
         while(R <= tR) Add(R++);
         while(R > tR + ) Remove(--R);
         Ans[q[i].id] = ans;
     }
     for(int i = ; i <= p; i++){
         printf("%d\n", Ans[i]);
     }
     return ;
 }

D-query