入门题
#include <stdio.h> #include <string.h> #include <iostream> #include <algorithm> #include <vector> #include <queue> #include <set> #include <map> #include <string> #include <math.h> #include <stdlib.h> #include <time.h> using namespace std; /* * 给出一个序列，查询区间内有多少个不相同的数 */ const int MAXN = 30010; const int M = MAXN * 100; int n,q,tot; int a[MAXN]; int T[M],lson[M],rson[M],c[M]; int build(int l,int r) { int root = tot++; c[root] = 0; if(l != r) { int mid = (l+r)>>1; lson[root] = build(l,mid); rson[root] = build(mid+1,r); } return root; } int update(int root,int pos,int val) { int newroot = tot++, tmp = newroot; c[newroot] = c[root] + val; int l = 1, r = n; while(l < r) { int mid = (l+r)>>1; if(pos <= mid) { lson[newroot] = tot++; rson[newroot] = rson[root]; newroot = lson[newroot]; root = lson[root]; r = mid; } else { rson[newroot] = tot++; lson[newroot] = lson[root]; newroot = rson[newroot]; root = rson[root]; l = mid+1; } c[newroot] = c[root] + val; } return tmp; } int query(int root,int pos) { int ret = 0; int l = 1, r = n; while(pos < r) { int mid = (l+r)>>1; if(pos <= mid) { r = mid; root = lson[root]; } else { ret += c[lson[root]]; root = rson[root]; l = mid+1; } } return ret + c[root]; } int main() { //freopen("in.txt","r",stdin); //freopen("out.txt","w",stdout); while(scanf("%d",&n) == 1) { tot = 0; for(int i = 1;i <= n;i++) scanf("%d",&a[i]); T[n+1] = build(1,n); map<int,int>mp; for(int i = n;i>= 1;i--) { if(mp.find(a[i]) == mp.end()) { T[i] = update(T[i+1],i,1); } else { int tmp = update(T[i+1],mp[a[i]],-1); T[i] = update(tmp,i,1); } mp[a[i]] = i; } scanf("%d",&q); while(q--) { int l,r; scanf("%d%d",&l,&r); printf("%d\n",query(T[l],r)); } } return 0; }