Count the string (KMP+DP)

Posted 2021-01-09 jaydenouyang

题目链接

 1 #include <bits/stdc++.h>
 2 using namespace std;
 3 typedef long long ll;
 4 
 5 inline int read()
 6 {
 7     int x=0,f=1;char ch=getchar();
 8     while(ch<‘0‘||ch>‘9‘){if(ch==‘-‘)f=-1;ch=getchar();}
 9     while(ch>=‘0‘&&ch<=‘9‘){x=x*10+ch-‘0‘;ch=getchar();}
10     return x*f;
11 }
12 
13 /********************************************************************/
14 
15 const int maxn = 1e6+6;
16 char s[maxn];
17 int Next[maxn];
18 int sum[maxn];
19 
20 const int mod = 10007;
21 
22 int main(){
23     int t; t = read();
24     while(t--){
25         int n; n = read();
26         scanf("%s", s+1);
27         //int len = strlen(s+1);
28         Next[1] = 0;;
29         int k = 0;
30         for(int i = 2;i <= n;i++){
31             while(k > 0 && s[k+1] != s[i]){
32                 k = Next[k];
33             }
34             if(s[k+1] == s[i])
35                 k++;
36             Next[i] = k;
37         }
38         int ans = 0;
39         memset(sum, 0, sizeof(sum));
40         for(int i = 1;i <= n;i++){
41             sum[i] = (sum[Next[i]] + 1)%mod;
42             ans = (ans + sum[i])%mod;
43         }
44         cout << ans << endl;
45     }
46     return 0;
47 }