莫队算法

 1 /*
 2   题意：
 3   思路：
 4   时间：
 5 */
 6 #include <bits/stdc++.h>
 7 using namespace std;
 8 
 9 typedef long long LL;
10 const int MAXN=100005;
11 const LL MOD7 = 1e9+7;
12 
13 struct Query
14 {
15     int l,r;
16     int idx;
17 }Q[MAXN];
18 
19 int a[MAXN];
20 int belong[MAXN],qsize,num;
21 LL flag[1<<20],Ans;
22 LL ans[MAXN];
23 int n,m,K;
24 
25 int cmp(Query oa,Query ob)
26 {
27     if (belong[oa.l]==belong[ob.l])
28         return oa.r<ob.r;
29     return belong[oa.l]<belong[ob.l];
30 }
31 
32 void Add(int x)
33 {
34     Ans+=flag[a[x]^K];
35     flag[a[x]]++;
36 }
37 void Delete(int x)
38 {
39     flag[a[x]]--;
40     Ans-=flag[a[x]^K];
41 }
42 int main()
43 {
44 #ifndef ONLINE_JUDGE
45     freopen("test.txt","r",stdin);
46 #endif // ONLINE_JUDGE
47     scanf("%d%d%d",&n,&m,&K);
48     qsize=sqrt(n);num=qsize;if (num*num<n) ++num;
49     for (int i=1;i<=n;++i)
50         belong[i]=(i-1)/qsize+1;
51     for (int i=1;i<=n;++i)
52     {
53         scanf("%d",&a[i]);
54         a[i]^=a[i-1];
55     }
56     int l=1,r=0;
57     Ans=0;
58     flag[0]=1;
59     for (int i=1;i<=m;++i)
60     {
61         scanf("%d%d",&Q[i].l,&Q[i].r);
62         Q[i].idx=i;
63     }
64     sort(Q+1,Q+1+m,cmp);
65     for (int i=1;i<=m;++i)
66     {
67         int idx=Q[i].idx;
68         while (l<Q[i].l) {Delete(l-1);++l;}
69         while (l>Q[i].l) {--l;Add(l-1);}
70         while (r<Q[i].r) {++r;Add(r);}
71         while (r>Q[i].r) {Delete(r);--r;}
72         ans[idx]=Ans;
73     }
74     for (int i=1;i<=m;++i)
75         printf("%I64d\n",ans[i]);
76     return 0;
77 }