题意：给你一个数组， q次询问， 每次询问都会有1个[l, r] 求 区间[1,l] 和 [r, n] 中 数字的种类是多少。
解法1， 莫队暴力：
代码：
1 #include<bits/stdc++.h> 2 using namespace std; 3 #define Fopen freopen("_in.txt","r",stdin); freopen("_out.txt","w",stdout); 4 #define LL long long 5 #define ULL unsigned LL 6 #define fi first 7 #define se second 8 #define pb push_back 9 #define lson l,m,rt<<1 10 #define rson m+1,r,rt<<1|1 11 #define max3(a,b,c) max(a,max(b,c)) 12 #define min3(a,b,c) min(a,min(b,c)) 13 typedef pair<int,int> pll; 14 const int inf = 0x3f3f3f3f; 15 const LL INF = 0x3f3f3f3f3f3f3f3f; 16 const LL mod = (int)1e9+7; 17 const int N = 2e5 + 100; 18 int n, m, blo; 19 int a[N]; 20 struct Node{ 21 int l, r, id, ans; 22 }q[N]; 23 bool cmp(Node x1, Node x2){ 24 if(x1.l/blo != x2.l / blo) return x1.l < x2.l; 25 if((x1.l / blo) & 1) return x1.r < x2.r; 26 else return x1.r > x2.r; 27 } 28 int cnt[N]; 29 int tot; 30 int ans[N]; 31 void add(int p){ 32 //cout << p << endl; 33 cnt[a[p]]++; 34 if(cnt[a[p]] == 1) tot++; 35 } 36 void Remove(int p){ 37 cnt[a[p]]--; 38 if(cnt[a[p]] == 0) tot--; 39 } 40 int main(){ 41 while(~scanf("%d%d", &n, &m)){ 42 memset(cnt, 0, sizeof(cnt)); 43 tot = 0; 44 blo = 500 + 1; 45 for(int i = 1; i <= n; i++) 46 scanf("%d", &a[i]); 47 for(int i = 1; i <= m; i++){ 48 scanf("%d%d", &q[i].l, &q[i].r); 49 q[i].id = i; 50 } 51 sort(q+1, q+1+m, cmp); 52 int L = 0, R = n+1; 53 for(int i = 1; i <= m; i++){ 54 int nl = q[i].l; 55 int nr = q[i].r; 56 while(L < nl) add(++L); 57 while(L > nl) Remove(L--); 58 while(R > nr) add(--R); 59 while(R < nr) Remove(R++); 60 ans[q[i].id] = tot; 61 } 62 for(int i = 1; i <= m; i++){ 63 printf("%d\n", ans[i]); 64 } 65 } 66 return 0; 67 }