codeforces 535D. Tavas and Malekas KMP

题目链接

又复习了一遍kmp....之前都忘光了

 1 #include<bits/stdc++.h>
 2 using namespace std;
 3 #define pb(x) push_back(x)
 4 #define ll long long
 5 #define mk(x, y) make_pair(x, y)
 6 #define lson l, m, rt<<1
 7 #define mem(a) memset(a, 0, sizeof(a))
 8 #define rson m+1, r, rt<<1|1
 9 #define mem1(a) memset(a, -1, sizeof(a))
10 #define mem2(a) memset(a, 0x3f, sizeof(a))
11 #define rep(i, a, n) for(int i = a; i<n; i++)
12 #define ull unsigned long long
13 typedef pair<int, int> pll;
14 const double PI = acos(-1.0);
15 const double eps = 1e-8;
16 const int mod = 1e9+7;
17 const int inf = 1061109567;
18 const int dir[][2] = { {-1, 0}, {1, 0}, {0, -1}, {0, 1} };
19 const int maxn = 1e6+5;
20 int next[maxn], a[maxn], vis[maxn], used[maxn];
21 char s[maxn];
22 void get_next() {
23     int len = strlen(s);
24     int i = 0, j = -1;
25     next[0] = -1;
26     while(i<len) {
27         if(j==-1 || s[i] == s[j]) {
28             i++, j++;
29             next[i] = j;
30         } else {
31             j = next[j];
32         }
33     }
34     int pos = next[len];
35     while(pos != -1) {
36         vis[pos] = 1;
37         pos = next[pos];
38     }
39     return ;
40 }
41 int main()
42 {
43     int n, m;
44     cin>>n>>m;
45     scanf("%s", s);
46     int len = strlen(s);
47     get_next();
48     for(int i = 1; i<=m; i++) {
49         scanf("%d", &a[i]);
50     }
51     sort(a+1, a+m+1);
52     int flag = 0;
53     for(int i = 1; i<=m; i++) {
54         if(i == 1 || a[i]-a[i-1]>len) {
55             for(int j = a[i]; j<len+a[i]; j++) {
56                 used[j] = 1;
57             }
58         } else {
59             if(vis[len+a[i-1]-a[i]]) {
60                 for(int j = a[i-1]+len; j<len+a[i]; j++) {
61                     used[j] = 1;
62                 }
63             } else {
64                 flag = 1;
65                 break;
66             }
67         }
68     }
69     if(flag) {
70         puts("0");
71         return 0;
72     }
73     ll ans = 1;
74     for(int i = 1; i<=n; i++) {
75         if(!used[i]) {
76             ans = (ans*26)%mod;
77         }
78     }
79     cout<<ans<<endl;
80     return 0;
81 }