Hope life better

#include <string>

using namespace std;

int (string s,string t)
{
    int i=0,j=0;
    while(i<s.length()&&j<t.length())
    {
        if(s[i]==t[j])
        {
            i++;
            j++;
        }
        else
        {
            i = i - j + 1;
            j = 0;
        }
    }
    if(j>=t.length()) return i-t.length();
    else
        return -1;
}
int * getNext(string t,int next[])//计算next数组
{
    next[0] = -1;
    int k=-1,i=0;
    while(i<t.length()-1)
    {
        if (k == -1 || t[i] == t[k])
        {
            if (t[i + 1] == t[k + 1])
            {
                next[++i] = next[++k];
            }
            else
            {
                next[++i] = ++k;
            }
        }
        else
        {
            k = next[k];
        }
    }
    return next;
}
int kmp(string s,string t)//kmp算法
{
    if(s=="" || t=="")
        return -1;
    int *next = new int[s.length()];
    getNext(t,next);

    int i=0;
    int j = -1;
    int t_len = t.length();
    int s_len = s.length();
    while( i < s_len && j < t_len)
    {
        if(j==-1||s[i]==t[j])
        {
            i++;
            j++;
        }
        else
        {
            j = next[j];
        }
    }
    if(j>=t.length())return i-t.length();
    else
        return -1;
}
int main() {
    string s,t;
    cin>>s>>t;
    cout<<Index(s,t)<<endl;
    cout<<kmp(s,t)<<endl;
    return 0;
}