hdu_5968_异或密码(预处理+二分)

 1 #include<bits/stdc++.h>
 2 #define F(i,a,b) for(int i=a;i<=b;i++)
 3 using namespace std;
 4 typedef long long ll;
 5 
 6 const int N=111;
 7 int t,dp[N],a[N],n,m,tp;
 8 
 9 
10 struct dt
11 {
12     int val,len;
13     bool operator<(const dt &b)const
14     {
15         return val<b.val;
16     }
17 }s[N*N],ttp;
18 bool cmp(dt a,dt b)
19 {
20     if(a.val==b.val)return a.len>b.len;
21     return a.val<b.val;
22 }
23 int main()
24 {
25     scanf("%d",&t);
26     while(t--)
27     {
28         scanf("%d",&n);
29         F(i,1,n)scanf("%d",a+i);
30         F(i,1,n)dp[i]=dp[i-1]^a[i];
31         int ed=0;
32         F(j,1,n)F(k,j,n)
33         {
34             s[++ed].val=dp[k]^dp[j-1];
35             s[ed].len=k-j+1;
36         }
37         sort(s+1,s+1+ed,cmp);
38         scanf("%d",&m);
39         F(i,1,m)
40         {
41             scanf("%d",&tp);
42             ttp.val=tp;
43             int now1=lower_bound(s+1,s+1+ed,ttp)-s,ans;
44             int now2=now1-1;
45             now2=lower_bound(s+1,s+1+ed,s[now2])-s;
46             if(now1>ed)now1=ed;
47             int n1=abs(s[now1].val-tp),n2=abs(s[now2].val-tp);
48             if(n1>n2)ans=now2;
49             else if(n1<n2)ans=now1;
50             else if(s[now1].len>s[now2].len)ans=now1;
51             else ans=now2;
52             printf("%d\n",s[ans].len);
53         }
54         puts("");
55     }
56     return 0;
57 }