BZOJ2743 [HEOI2012]采花

本来想做这道题的。。。后来发现根本搞不懂

于是又滚回了BZOJ 1878搞了搞。。。

发现这道题和1878差不多，只是要注意update的时候要加个next

其实我们可以推广到3个、4个、5个（貌似可以用倍增？感觉可以出一道题呢、、、）

然后就没有然后啦~，不要问我为什么用了fread。。。只是无聊了≥v≤~

 

 1 /**************************************************************
 2     Problem: 2743
 3     User: rausen
 4     Language: C++
 5     Result: Accepted
 6     Time:3940 ms
 7     Memory:56472 kb
 8 ****************************************************************/
 9  
10 #include <cstdio>
11 #include <algorithm>
12  
13 #define lowbit(x) x & -x
14 using namespace std;
15 const int N = 1000005;
16 const int Maxlen = 25 * N;
17 struct data{
18     int l, r, w;
19     inline bool operator < (const data &x) const {
20         return l == x.l ? r < x.r : l < x.l;
21     }
22 } q[N];
23  
24 int n, m, c;
25 int a[N], next[N], first[N];
26 int BIT[N];
27 int ans[N];
28  
29 char buf[Maxlen], *C = buf;
30 int Len;
31 inline int read() {
32     int x = 0;
33     while (*C < '0' || '9' < *C) ++C;
34     while ('0' <= *C && *C <= '9')
35         x = x * 10 + *C - '0', ++C;
36     return x;
37 }
38  
39 int L, pr[10];
40 void print(int x) {
41     if (!x) {
42         puts("0");
43         return;
44     }
45     while (x)
46         pr[++L] = x % 10, x /= 10;
47     while (L)
48         putchar(pr[L--] + '0');
49     putchar('\n');
50 }
51  
52 void update(int x, int v) {
53     if (!x) return;
54     while (x <= n)
55         BIT[x] += v, x += lowbit(x);
56 }
57   
58 int query(int x) {
59     int res = 0;
60     while (x)
61         res += BIT[x], x -= lowbit(x);
62     return res;
63 }
64  
65 int main() {
66     int i, l;
67     Len = fread(C, 1, Maxlen, stdin);
68     buf[Len] = '\0';
69     n = read(), c = read(), m = read();
70     for (i = 1; i <= n; ++i)
71         a[i] = read();
72     for (i = n; i; --i)
73         next[i] = first[a[i]], first[a[i]] = i;
74     for (i = 1; i <= c; ++i)
75         update(next[first[i]], 1);
76  
77     for (i = 1; i <= m; ++i)
78         q[i].l = read(), q[i].r = read(), q[i].w = i;
79     sort(q + 1, q + m + 1);
80     for (i = l = 1; i <= m; ++i) {
81         for (; l < q[i].l; ++l)
82             update(next[l], -1), update(next[next[l]], 1);
83         ans[q[i].w] = query(q[i].r) - query(q[i].l - 1);
84     }
85     for (i = 1; i <= m; ++i)
86         print(ans[i]);
87     return 0;
88 }
View Code

 

posted on 2014-12-14 11:35  Xs酱~  阅读(319)  评论(0)  编辑  收藏  举报