题目链接:http://poj.org/problem?id=3461
简单明了KMP,不过需要统计出现的次数。
在每次查询到一个的时候依旧要沿着失配边走而不是直接回到开头。
代码:
1 #include <cstdio> 2 #include <cstdlib> 3 #include <cmath> 4 #include <cstring> 5 #include <algorithm> 6 #include <string> 7 #include <queue> 8 #include <stack> 9 #include <map> 10 #include <set> 11 #include <vector> 12 #include <functional> 13 using namespace std; 14 #define inf 0x3f3f3f3f 15 #define maxn 2051 16 17 18 19 int getFail(char p[], int f[]){ 20 f[0] = f[1] = 0; 21 int len = strlen(p); 22 for(int i = 1; i < len; i++){ 23 int j = f[i]; 24 while(j && p[i] != p[j]) j = f[j]; 25 f[i + 1] = (p[i] == p[j]? j + 1: 0); 26 } 27 return 0; 28 } 29 int KMP(char t[], char p[], int f[]){ 30 getFail(p, f); 31 int tlen = strlen(t), plen = strlen(p); 32 bool flag = false; 33 int rec = 0; 34 for(int i = 0, j = 0; i < tlen; i++){ 35 while(j && p[j] != t[i]) 36 j = f[j]; 37 if(p[j] == t[i]) 38 j++; 39 if(j == plen){ 40 flag = true; 41 rec++; j = f[j]; 42 continue; 43 } 44 } 45 46 47 return rec; 48 } 49 char t[1000005], p[10005]; 50 int f[10005]; 51 int main(){ 52 int tp; 53 scanf("%d", &tp); 54 while(tp--){ 55 scanf("%s %s", p, t); 56 memset(f, 0, sizeof(f)); 57 int res = KMP(t, p, f); 58 printf("%d ", res); 59 } 60 }
题目:
Time Limit: 1000MS | Memory Limit: 65536K | |
Total Submissions: 40186 | Accepted: 16146 |
Description
The French author Georges Perec (1936–1982) once wrote a book, La disparition, without the letter 'e'. He was a member of the Oulipo group. A quote from the book:
Tout avait Pair normal, mais tout s’affirmait faux. Tout avait Fair normal, d’abord, puis surgissait l’inhumain, l’affolant. Il aurait voulu savoir où s’articulait l’association qui l’unissait au roman : stir son tapis, assaillant à tout instant son imagination, l’intuition d’un tabou, la vision d’un mal obscur, d’un quoi vacant, d’un non-dit : la vision, l’avision d’un oubli commandant tout, où s’abolissait la raison : tout avait l’air normal mais…
Perec would probably have scored high (or rather, low) in the following contest. People are asked to write a perhaps even meaningful text on some subject with as few occurrences of a given “word” as possible. Our task is to provide the jury with a program that counts these occurrences, in order to obtain a ranking of the competitors. These competitors often write very long texts with nonsense meaning; a sequence of 500,000 consecutive 'T's is not unusual. And they never use spaces.
So we want to quickly find out how often a word, i.e., a given string, occurs in a text. More formally: given the alphabet {'A', 'B', 'C', …, 'Z'} and two finite strings over that alphabet, a word W and a text T, count the number of occurrences of W in T. All the consecutive characters of W must exactly match consecutive characters of T. Occurrences may overlap.
Input
The first line of the input file contains a single number: the number of test cases to follow. Each test case has the following format:
- One line with the word W, a string over {'A', 'B', 'C', …, 'Z'}, with 1 ≤ |W| ≤ 10,000 (here |W| denotes the length of the string W).
- One line with the text T, a string over {'A', 'B', 'C', …, 'Z'}, with |W| ≤ |T| ≤ 1,000,000.
Output
For every test case in the input file, the output should contain a single number, on a single line: the number of occurrences of the word W in the text T.
Sample Input
3 BAPC BAPC AZA AZAZAZA VERDI AVERDXIVYERDIAN
Sample Output
1 3 0