HDU 1711 Number Sequence（KMP模板）

http://acm.hdu.edu.cn/showproblem.php?pid=1711

这道题就是一个KMP模板。

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

const int maxn = 1000000+5;

int n,m;

int next[maxn];
int a[maxn], b[maxn];

void get_next()
{
    int i = -1, j = 0;
    ::next[0] = -1;
    while (j < m)
    {
        if (i == -1 || b[i] == b[j])
            ::next[++j] = ++i;
        else
            i = ::next[i];
    }
}


int kmp()
{
    int i = 0, j = 0;
    while (i < n)
    {
        if (j == -1 || a[i] == b[j])
        {
            i++;
            j++;
        }
        else
            j = ::next[j];
        if (j == m)
            return i;
    }
    return -1;
}

int main()
{
    //freopen("D:\txt.txt", "r", stdin);
    int t;
    cin >> t;
    while (t--)
    {
        cin >> n >> m;
        for (int i = 0; i < n; i++)
            cin >> a[i];
        for (int i = 0; i < m; i++)
            cin >> b[i];
        get_next();
        int k=kmp();
        if (k!=-1)  cout << k-m+1 << endl;
        else cout << "-1" << endl;
    }
    return 0;
}