[luoguP2709] 小B的询问（莫队）

 1 #include <cmath>
 2 #include <cstdio>
 3 #include <iostream>
 4 #include <algorithm>
 5 
 6 const int MAXN = 50001;
 7 int n, m, S, k, ans = 1;
 8 int a[MAXN], ton[MAXN], anslist[MAXN];
 9 struct node
10 {
11     int l, r, id, num;
12 }q[MAXN];
13 
14 inline int read()
15 {
16     int x = 0;
17     char ch = getchar();
18     for(; !isdigit(ch); ch = getchar());
19     for(; isdigit(ch); ch = getchar()) x = (x << 1) + (x << 3) + ch - ‘0‘;
20     return x;
21 }
22 
23 inline bool cmp(node x, node y)
24 {
25     return x.id ^ y.id ? x.id < y.id : x.r < y.r;
26 }
27 
28 int main()
29 {
30     int i, x, y;
31     n = read();
32     m = read();
33     k = read();
34     S = sqrt(n);
35     for(i = 1; i <= n; i++) a[i] = read();
36     for(i = 1; i <= m; i++) q[i].l = read(), q[i].r = read(), q[i].num = i;
37     for(i = 1; i <= m; i++) q[i].id = q[i].l / S + 1;
38     std::sort(q + 1, q + m + 1, cmp);
39     x = q[1].l, y = q[1].l;
40     ton[a[x]]++;
41     for(i = 1; i <= m; i++)
42     {
43         while(x < q[i].l)
44         {
45             ton[a[x]]--;
46             ans -= ton[a[x]] << 1 | 1;
47             x++;
48         }
49         while(x > q[i].l)
50         {
51             x--;
52             ans += ton[a[x]] << 1 | 1;
53             ton[a[x]]++;
54         }
55         while(y > q[i].r)
56         {
57             ton[a[y]]--;
58             ans -= ton[a[y]] << 1 | 1;
59             y--;
60         }
61         while(y < q[i].r)
62         {
63             y++;
64             ans += ton[a[y]] << 1 | 1;
65             ton[a[y]]++;
66         }
67         anslist[q[i].num] = ans;
68     }
69     for(i = 1; i <= m; i++) printf("%d\n", anslist[i]);
70     return 0;
71 }