C++实现KMP模式匹配算法

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#include<iostream>#include<string>#include<vector>using namespace std; void Next(const string & pat,vector<int> & next){next.resize(pat.length());if(pat.length() == 0) return;next[0] = -1;for(size_t pos = 1; pos < pat.length(); ++pos){size_t sublen = pos-1;while(sublen >= 0){if(pat.substr(0, sublen) == pat.substr(pos-sublen+1, sublen))break;--sublen;}next[pos] = sublen;}return;}int main(void){string str1, str2;while(cin >> str1 >> str2) {vector<int> next;Next(str2, next);vector<int> pos;int i = 0, j1 = 0, j2 = 0;while(j1 < str1.length()) {j2 = j1 - i;if(j2 >= str2.length()) {// foundpos.push_back(i);// move on;int delta = str2.length();i = i + delta;j1 = max(i,j1);}else if(str1[j1] == str2[j2]) {++j1;}else { // str1[j1] != str2[j2];int delta = j2 - next[j2];i = i + delta;j1 = max(i,j1);}}//output.cout << "str1.length(): " << str1.length() << endl;cout << "str2.length(): " << str2.length() << endl;cout << "str1 from pos: " << endl;for(int i = 0; i < pos.size(); ++i) cout << "[" << (i+1) << "]: " << str1.substr(pos[i], string::npos) << endl;cout << "str2: " << str2 << endl;}return 0;}

参考自： http://www.cnblogs.com/BeyondAnyTime/archive/2012/07/09/2583133.html

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