HDU 1686 Oulippo

Posted 2020-08-29 谦谦君子，陌上其华

 

http://acm.hdu.edu.cn/showproblem.php?pid=1686

题意：给定一个文本串和给定一个模式串，求文本串中有几个模式串。

思路：直接套用KMP模板。

 1 #include<iostream> 
 2 #include<cstring>
 3 #include<string>
 4 using namespace std;
 5 
 6 const int maxn = 1000000 + 5;
 7 
 8 int next[10002], n, m;
 9 char text[maxn], pattern[10002];
10 
11 void get_next()
12 {
13     int i, j;
14     i = -1;
15     j = 0;
16     ::next[0] = -1;
17     while (j<m)
18     {
19         if (i == -1 || pattern[i] == pattern[j])
20         {
21             ::next[++j] = ++i;
22         }
23         else
24             i = ::next[i];
25     }
26 }
27 
28 int KMP()
29 {
30     int i, j, count = 0;
31     i = j = 0;
32     get_next();
33     while (i<n)
34     {
35         if (j == -1 || text[i] == pattern[j])
36         {
37             i++;
38             j++;
39             if (j == m)  count++;
40         }
41         else
42             j = ::next[j];
43     }
44     return count;
45 }
46 
47 int main()
48 {
49     //freopen("D:\\txt.txt", "r", stdin);
50     int t, ans;
51     cin >> t;
52     getchar();
53     while (t--)
54     {
55         scanf("%s", pattern);
56         scanf("%s", text);
57         n = strlen(text);
58         m = strlen(pattern);
59         ans = KMP();
60         cout << ans << endl;
61     }
62     return 0;
63 }