杭电 hdu 2087 剪花布条

最新推荐文章于 2025-12-02 20:42:11 发布

最新推荐文章于 2025-12-02 20:42:11 发布 · 121 阅读

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#c/c++ #php

本文分享了一次使用KMP算法解决字符串匹配问题的经历，并对比了两种不同的实现方式。通过对比，作者反思了初次实现中存在的不足，并展示了如何利用标准库函数简化代码。

第二次做这题，才发现，这一题的数据真是水得可以，连第一次本应错误的代码也能过……第一次在kmp() 函数里面，在if( len == j ) 之后本应是 { ++cnt ; j = 0 ; } 才对。

/* THE PROGRAM IS MADE BY PYY */ /*----------------------------------------------------------------------------// Copyright (c) 2011 panyanyany All rights reserved. URL : http://acm.hdu.edu.cn/showproblem.php?pid=2087 Name : 2087 剪花布条 Date : Wednesday, August 17, 2011 Time Stage : half an hours around Result: Test Data: 4440850 2011-08-17 21:55:06 Accepted 2087 0MS 200K 1590 B C++ pyy Review: 确实不太难，现在却理解不了以前的做法了，好奇怪……又变得懵懂了我…… //----------------------------------------------------------------------------*/ #include <stdio.h> #include <string.h> #define max(a, b) (((a) > (b)) ? (a) : (b)) #define min(a, b) (((a) < (b)) ? (a) : (b)) #define infinity 0x7f7f7f7f #define minus_inf 0x80808080 #define MAXSIZE 1009 char model[MAXSIZE], pattn[MAXSIZE] ; int next[MAXSIZE], len_1, len_2 ; void getNext (char *ps, char *pe) { int i, j ; i = 0 ; j = -1 ; next[0] = -1 ; while (i < pe - ps) { if (j == -1 || ps[i] == ps[j]) { ++i ; ++j ; if (ps[i] != ps[j]) next[i] = j ; else next[i] = next[j] ; } else { j = next[j] ; } } } int kmp (char *ms, char *me, char *ps, char *pe) { int i, j, cnt ; i = j = cnt = 0 ; getNext (ps, pe) ; while (i < me - ms) { if (j == -1 || ms[i] == ps[j]) { ++i ; ++j ; } else { j = next[j] ; } if (j == pe - ps) { ++cnt ; j = 0 ; } } return cnt ; } int main () { while (scanf ("%s", model), *model != '#') { scanf ("%s", pattn) ; getchar () ; printf ("%d\n", kmp (model, model +strlen (model), pattn, pattn + strlen (pattn))) ; } return 0 ; }

--------------------------------------------第一次的分割线-------------------------------------------------------

不搜不知道，一搜吓一跳！原来这题：1.可以不用KMP算法做，2.可以调用库函数来做！

/* THE PROGRAM IS MADE BY PYY */ /*----------------------------------------------------------------------------// Copyright (c) 2011 panyanyany All rights reserved. URL : http://acm.hdu.edu.cn/showproblem.php?pid=2087 Name : 2087 剪花布条 Date : Monday, May 6, 2011 Time Stage : half an hours around Result: Test Data: 3929798 2011-05-09 02:40:39 Accepted 2087 15MS 280K 1215 B C++ pyy Review: 貌似是一题比较简单的KMP //----------------------------------------------------------------------------*/ #include <iostream> #include <string.h> #include <stdio.h> using namespace std; const int size = 1010; char str[size], piece[size]; int next[size]; void getNext() { int i, j, k; const int len = (int)strlen(piece); i = 0; j = 1; next[0] = -1; while( j < len ) { if( piece[i] == piece[j] ) { next[j] = next[i]; ++i; } else { next[j] = i; } ++j; } } int kmp() { int i, j; int cnt = 0; const int leng = strlen(str), len = strlen(piece); getNext(); for( i = j = 0; i < leng; ) { if( len == j ) ++cnt; if( str[i] == piece[j] || -1 == j ) { ++i; ++j; } else { j = next[j]; } } if( leng == i && len == j ) ++cnt; return cnt; } int main() { int i, j; while( cin >> str >> piece && strcmp(str, "#") ) { cout << kmp() << endl; } return 0; }