hdu1171kmp果题

Posted 2021-03-05 randy-lo

题目链接：http://icpc.njust.edu.cn/Problem/Hdu/1711/

 1 #include<bits/stdc++.h>
 2 using namespace std;
 3 typedef unsigned int ui;
 4 typedef long long ll;
 5 typedef unsigned long long ull;
 6 #define pf printf
 7 #define mem(a,b) memset(a,b,sizeof(a))
 8 #define prime1 1e9+7
 9 #define prime2 1e9+9
10 #define pi 3.14159265
11 #define lson l,mid,rt<<1
12 #define rson mid+1,r,rt<<1|1
13 #define scand(x) scanf("%llf",&x) 
14 #define f(i,a,b) for(int i=a;i<=b;i++)
15 #define scan(a) scanf("%d",&a)
16 #define dbg(args) cout<<#args<<":"<<args<<endl;
17 #define inf 0x3f3f3f3f
18 #define maxn 1000010
19 int n,m,t;
20 int a[maxn],b[maxn],nxt[maxn];
21 void getnxt()
22 {
23     nxt[0]=-1;
24     int i=-1,j=0;
25     while(j<m)
26     {
27         if(i==-1||b[i]==b[j])
28         {
29             i++,j++;
30             if(b[i]==b[j])nxt[j]=nxt[i];
31             else nxt[j]=i;
32         }
33         else i=nxt[i];
34     }
35 }
36 int kmp()
37 {
38     int i=0,j=0;
39     while(i<n)
40     {
41         if(j==-1||a[i]==b[j])i++,j++;
42         else j=nxt[j];
43         if(j==m)
44         {
45             return i-m+1;
46         }
47     }
48     return -1;
49 }
50 int main()
51 {
52     //freopen("input.txt","r",stdin);
53     //freopen("output.txt","w",stdout);
54     std::ios::sync_with_stdio(false);
55     scan(t);
56     while(t--)
57     {
58         scan(n);
59         scan(m);
60         f(i,0,n-1)scan(a[i]);
61         f(i,0,m-1)scan(b[i]);
62         getnxt();
63         pf("%d
",kmp());
64     }
65  }