kmp算法

直接把求next数组跟标记平移放到一起

#include <iostream>
#include <vector>
#include <stdlib.h>
using namespace std;

bool kmp( vector<char>& str1, vector<char>& str2 ) {
    vector<int> next(str2.size());

    int i = 1;
    int k = 0;

    while ( i < str2.size() ) {
        if ( str2[i] == str2[k] ) {
            next[i] = next[i-1]+1;
            i++;
            k++;
        }
        else {
            k = next[i++];   // write like "k = 0; i++;" is easier to understand
        }
    }

    for (int j = 0; j < next.size() ; ++j) {
        cout << next[j] << " " ;
    }

    int begin = 0;
    while ( begin + str2.size() <= str1.size() ) {
        int same = 0;
        while ( str1[begin+same] == str2[same] ) {
            same++;
            if ( same == str2.size() ) {
                return true;
            }

        }
        if ( same == 0 )
            begin++;
        else {
            begin +=  same - next[same - 1];
        }
    }
    return false;
}

int main() {
    char a[8] = { 'a','b', 'a','b','a', 'b','c','a'};
    char b[16] ="bacbabababcabab";
    vector<char> str1(b,b+16);
    vector<char> str2(a,a+8);
    bool result = kmp(str1,str2);
    cout << result << endl;
}