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;
}

#include<iostream>
#include<vector>
using namespace std;


void calculatePrefix(string& s,vector<int>& prefix){
    int i = 0;
    int j = 1;
    prefix[i] = 0;
    while(j < s.size()){
        if(s[i] == s[j]){
            prefix[j++] = ++i;
        }else{
            if(i > 0) i = prefix[i-1];
            else {
                prefix[j] = 0;
                j++;
            }
        }
    }
    for(int x = s.size()-2;x>=0;x--){
        prefix[x+1] = prefix[x];
    }
    prefix[0] = -1;
}

int searchSubStrByKmp(string& text,string& pattern,vector<int>& prefix){
    int i = 0,j = 0;
    while (i < text.size())
    {
        if(j == pattern.size() - 1 && text[i] == pattern[j]){
            return i - pattern.size() + 1;
        }
        if(text[i] == pattern[j]) {
            i++;
            j++;
        }else{
            j = prefix[j];
            if (j == -1) {
                i++;
                j++;
            }          
        }
    }
    return -1;
}

int main(){
    string s = "ABBBBBBBBC";
    string t = "BBBBBC";
    vector<int> prefix(t.size());
    calculatePrefix(t,prefix);
    // for(int num:prefix){
    //     cout << num << " ";
    // }
    // cout << endl;
    cout << searchSubStrByKmp(s,t,prefix) << endl;
    return 0;
}