条件:无
题目:无
原理:无
代码:
/* * Author: Moota * Copyright: Moota * Description: Written by Moota */ #include <iostream> //cin,cout #include <iomanip> //fixed<<setprecision(2) #include <algorithm> //sort #include <map> #include <queue> #include <stack> #include <deque> //双端队列,头可插,尾可插 #include <string> #include <cstring> #include <cmath> //sqrt,abs #include <fstream> //file #include <ctime> #include <climits> //数值极限 //(double)clock() / CLOCKS_PER_SEC <= 1 限制1s跑完程序 using namespace std; class Solver { public: Solver() { //取消和c输出输入的同步,加快读取 ios::sync_with_stdio(false); cin.tie(nullptr); cout.tie(nullptr); //誓死捍卫c++的风格 } public: void SaveCpp(string name) const { fstream input; fstream output; input.open("moota.cpp", ios::in); output.open(name.c_str(), ios::out); char c = 'O'; while (!input.eof()) { input.get(c); output << c; } input.close(); output.close(); } protected: virtual void BeginPlay() { }; virtual void Playing() { }; virtual void EndPlay() { }; public: void Play() { BeginPlay(); Playing(); EndPlay(); } }; class SpecialSolver : public Solver { public: typedef long long int lld; typedef unsigned long long int ulld; static const lld MAX = static_cast<lld>(1e4); static const lld INF = static_cast<lld>(1e18); private: string text, pattern; int kmp[MAX]; private: //朴素匹配 void Normal() { const int aSize = text.size() - 1; const int bSize = pattern.size() - 1; for (int i = 1; i <= aSize; ++i) { int k = i; for (int j = 1; j <= bSize; ++j) { if (text[k] != pattern[j]) { break; } else { ++k; if (j == bSize) { cout << i << " "; } } } } } //KMP数组 void GetKMP() { kmp[0] = 0; //简单的认为一个字符不具有前后缀。 kmp[1] = 0; //len:和自身匹配的字符串的下标。 //len:也是最长的相同前后缀长度。 //kmp[len]:到len位置为止(包括len)最大的相同前后缀长度 int len = 0; const int aSize = pattern.size() - 1; for (int i = 2; i <= aSize; ++i) { //失配后,本来嘛,最大长度要直接回到0, //聪明的KMP知道这一段完全匹配,虽然失配了 //但是1-j这段字符串有相同的前后缀, //所以跳到0不如跳到最长前缀的结束的那里。 //比如: //abcabefg //abcabg //pattern[i]=e,pattern[len+1]=g时失配 //一看 kmp[len]等于 2, //那么回去 pattern[len]=b,pattern[len+1]=c //这样只要比较 pattern[i]=e和 pattern[len+1]=c //不用从头比较了,为什么? //因为此时的最大前后缀 //text前缀(ab)=pattern后缀(ab),前后缀相等,无需比较。 while (len > 0 && pattern[i] != pattern[len + 1]) { len = kmp[len]; } //len+1 表示想要扩展,即将扩展的地方相等,就可以扩展 if (pattern[i] == pattern[len + 1]) { ++len; kmp[i] = len; } } } //KMP 匹配 void DoKMP() { int len = 0; //此时文本串就不是自身了 const int aSize = text.size() - 1; const int bSize = pattern.size() - 1; //现在是匹配文本串,每一位都要匹配,所以从1开始。 for (int i = 1; i <= aSize; ++i) { while (len > 0 && text[i] != pattern[len + 1]) { len = kmp[len]; } if (text[i] == pattern[len + 1]) { ++len; if (len == bSize) { cout << i - bSize + 1 << " "; len = kmp[len]; } } } } protected: virtual void BeginPlay() override { Solver::BeginPlay(); //注意修改文件名称 //SaveCpp("KMP匹配.cpp"); cin >> text >> pattern; text = " " + text; pattern = " " + pattern; }; virtual void Playing() override { Solver::Playing(); //abcabcabc abc cout << "\n朴素匹配:"; Normal(); cout << "\nKMP匹配:"; GetKMP(); DoKMP(); }; virtual void EndPlay() override { Solver::EndPlay(); }; }; SpecialSolver specialSolver; int main() { specialSolver.Play(); }