KMP算法解决字符串匹配问题

#include<iostream>

using namespace std;

int nextn[100];

void get_next(string t){
    int m = t.size();
    for(int i = 1; i < m; i ++){
        int j = nextn[i];
        while(j > 0 and t[i] != t[j]){
            j = nextn[j];
        }
        if(t[i] == t[j])
            nextn[i + 1] = j + 1;
        else
            nextn[i + 1] = 0;
    }
}

int get_anwser(string s, string t){
    int ans = 0, j = 0;
    int m = s.size();
    int n = t.size();
    for(int i = 0; i < m; i ++){
        while(j > 0 and s[i] != t[j])
            j = nextn[j];
        if(s[i] == t[j])
            j += 1;
        if(j == n){
            ans += 1;
            j = nextn[j];
        }
    }
    return ans;
}

int main(){
    string s, t;
    cin >> s >> t;
    if((int)s.size() < (int)t.size()) swap(s, t);
    s += s;
    get_next(t);
    if(get_anwser(s, t))
        cout << "true" << endl;
    else
        cout << "false" << endl;
    return 0;

}