POJ 3461 Oulipo
Time Limit: 1000MS | Memory Limit: 65536K | |
Total Submissions: 16111 | Accepted: 6482 |
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
题目大意:求一个字符串中另一个字符串出现的次数
#include <stdio.h> #include <string> #include <string.h> #include <cstring> using namespace std; int arr[1000005]; char str1[1000005]; char str2[1000005]; void getindex(char deststr[], int index[]) { int nLen = strlen(deststr); int k = -1; int j = 0; index[0] = -1; while(j < nLen) { if (k == -1 || deststr[k] == deststr[j]) { k++; j++; index[j] = k; } else { k = index[k]; } } } int KMP(char srcstr[], char deststr[]) { int nLen1 = strlen(srcstr); int nLen2 = strlen(deststr); getindex(deststr, arr); int i = 0; int j = 0; int nCount = 0; while(i < nLen1) { if (srcstr[i] == deststr[j] || j == -1) { i++; j++; if (j == nLen2) { nCount ++; } } else { j = arr[j]; } } return nCount; } int main() { int n; scanf("%d", &n); for (int i = 0; i < n; i++) { scanf("%s%s", str1, str2); printf("%d\n", KMP(str2, str1)); } return 0; }