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1 //hdu2087 2 #include <iostream> 3 #include <string> 4 #include <cstring> 5 using namespace std; 6 string str1,str2; 7 int next[1005]; 8 void get() 9 { 10 int i = 0; 11 int j = -1; 12 memset(next,0,sizeof(next)); 13 next[0] = -1;//不加的话会死循环,因为 j = next[j]（j=0） 会赋一个垃圾数字 14 while(i<str2.length()) 15 { 16 if(j==-1||str2[i]==str2[j]) 17 { 18 i++; 19 j++; 20 next[i] = j; 21 } 22 else 23 j = next[j]; 24 } 25 } 26 int kmp() 27 { 28 int i = 0, j = 0; 29 int cnt = 0; 30 while(i<str1.length()) 31 { 32 if(j==-1||str1[i]==str2[j]) 33 { 34 i++; 35 j++; 36 if(j==str2.length()) 37 { 38 cnt++; 39 j=0; 40 } 41 } 42 else 43 j = next[j]; 44 } 45 return cnt; 46 } 47 int main() 48 { 49 while(cin>>str1) 50 { 51 if(str1[0]=='#') 52 break; 53 cin>>str2; 54 get(); 55 int cnt = kmp(); 56 cout<<cnt<<endl; 57 str1.clear(); 58 str2.clear(); 59 } 60 return 0; 61 }
1 //模式串在主串中出现次数 2 //估计find会超时 3 //不论哪一个next函数均可ＡＣ 4 #include <iostream> 5 #include <cstring> 6 #include <string> 7 using namespace std; 8 string s1,s2; 9 int next[10005]; 10 void get() 11 { 12 int i = 0; 13 int j = -1; 14 memset(next,0,sizeof(next)); 15 next[0] = -1;//不加的话会死循环,因为 j = next[j]（j=0） 会赋一个垃圾数字 16 while(i<s1.length()) 17 { 18 if(j==-1||s1[i]==s1[j]) 19 { 20 i++; 21 j++; 22 // if(s1[i]!=s1[j]) 23 next[i] = j; 24 // else 25 // next[i] = next[j]; 26 } 27 else 28 j = next[j]; 29 } 30 } 31 int kmp() 32 { 33 int i = 0, j = 0; 34 int cnt = 0; 35 while(i<s2.length())//(i<=(s2.length()-s1.length()))不行 36 { 37 if(j==-1||s1[j]==s2[i]) 38 { 39 i++; 40 j++; 41 } 42 else 43 j = next[j]; 44 if(j==s1.length()) 45 { 46 cnt++; 47 j = next[j];//此处改为j = 0就变成减花布条那一题啦 48 } 49 } 50 return cnt; 51 } 52 int main() 53 { 54 int i,j,k,T; 55 cin>>T; 56 while(T--) 57 { 58 s1.clear(); 59 s2.clear(); 60 cin>>s1; 61 cin>>s2; 62 get(); 63 int cnt = kmp(); 64 cout<<cnt<<endl; 65 } 66 return 0; 67 } 68 69
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//超时，即便全为C风格也超时 #include <iostream> #include <cstring> #include <string> using namespace std; string s1,s2; int next[10005]; void get() { int i = 0; int j = -1; memset(next,0,sizeof(next)); next[0] = -1;//不加的话会死循环,因为 j = next[j]（j=0） 会赋一个垃圾数字 while(i<s1.length()) { if(j==-1||s1[i]==s1[j]) { i++; j++; if(s1[i]!=s1[j]) next[i] = j; else next[i] = next[j]; } else j = next[j]; } } int kmp() { int i = 0, j = 0; int cnt = 0; while(i<s2.length())//(i<=(s2.length()-s1.length()))不行 { if(j==-1||s1[j]==s2[i]) { i++; j++; if(j==s1.length()) { cnt++; i = i-j+1; j = 0; } } else j = next[j]; } return cnt; } int main() { int i,j,k,T; cin>>T; while(T--) { s1.clear(); s2.clear(); cin>>s1; cin>>s2; get(); int cnt = kmp(); cout<<cnt<<endl; } return 0; }