kmp算法板子

#include<iostream>
using namespace std;
void makePrefixTable(string pattern,int prefix[],int size){
    //我们都是生活在阴沟里的人,但仍有人仰望星空。
    //永远相信美好的事情明天即将发生。
    prefix[0] = 0;
    int i = 1;
    int len = 0;
    while(i<size){
        if(pattern[i] == pattern[len]){
            len++;
            prefix[i] = len;
            i++;
        }else{
            if(len>0){
                len = prefix[len - 1];
            }else{
                prefix[i] = 0;
                i++;
            }
            // cout << "i:" << i << endl;
        }
    }
    // cout << endl;
    // for(int i=0;i<size;i++){
    //     cout << prefix[i] << " ";
    // }
    cout << endl;
    for(int i=size-2;i>=0;i--){
        prefix[i+1] = prefix[i];
        // cout << "i:"<<i << endl;
    }
    prefix[0] = -1;
}
void kmp(string text,string pattern,int prefix[]){
    int i = 0;
    int j = 0;
    while(i<text.size()){
        if(j==pattern.size()-1 && text[i] == pattern[j]){
            cout << "Found string at: "<<i-j << endl;
            j = prefix[j];
        }
        if(text[i]==pattern[j]){
            i++;
            j++;
        }else{
            j = prefix[j];
            if(j==-1){
                i++;
                j++;
            }
        }
    }

}
int main(){
    string s = "ABBBBBBBBC";
    string t = "BBBBBC";
    int size = t.size();
    int array[size];
    makePrefixTable(t,array,size);
    kmp(s,t,array);
    cout << endl;
    return 0;
}
posted @ 2021-08-26 11:43  DaWeiGuo  阅读(75)  评论(0编辑  收藏  举报