[luoguP1972] [SDOI2009]HH的项链（莫队）

 1 #include <cmath>
 2 #include <cstdio>
 3 #include <iostream>
 4 #include <algorithm>
 5 
 6 int n, m, S, ans = 1;
 7 int a[50001], ton[1000001], anslist[200001];
 8 struct node
 9 {
10     int l, r, id, num;
11 }q[200001];
12 
13 inline int read()
14 {
15     int x = 0;
16     char ch = getchar();
17     for(; !isdigit(ch); ch = getchar());
18     for(; isdigit(ch); ch = getchar()) x = (x << 1) + (x << 3) + ch - ‘0‘;
19     return x;
20 }
21 
22 inline bool cmp(node x, node y)
23 {
24     return x.id ^ y.id ? x.id < y.id : x.r < y.r;
25 }
26 
27 int main()
28 {
29     int i, x, y;
30     n = read();
31     for(i = 1; i <= n; i++) a[i] = read();
32     m = read();
33     for(i = 1; i <= m; i++) q[i].l = read(), q[i].r = read(), q[i].num = i;
34     S = sqrt(n);
35     for(i = 1; i <= m; i++) q[i].id = q[i].l / S + 1;
36     std::sort(q + 1, q + m + 1, cmp);
37     x = q[1].l, y = q[1].l;
38     ton[a[x]]++;
39     for(i = 1; i <= m; i++)
40     {
41         while(x < q[i].l)
42         {
43             ton[a[x]]--;
44             if(!ton[a[x]]) ans--;
45             x++;
46         }
47         while(x > q[i].l)
48         {
49             x--;
50             if(!ton[a[x]]) ans++;
51             ton[a[x]]++;
52         }
53         while(y > q[i].r)
54         {
55             ton[a[y]]--;
56             if(!ton[a[y]]) ans--;
57             y--;
58         }
59         while(y < q[i].r)
60         {
61             y++;
62             if(!ton[a[y]]) ans++;
63             ton[a[y]]++;
64         }
65         anslist[q[i].num] = ans;
66     }
67     for(i = 1; i <= m; i++) printf("%d\n", anslist[i]);
68     return 0;
69 }