HDU 3336(KMP)

题目链接：http://acm.hdu.edu.cn/showproblem.php?pid=3336

考查next数组的应用和理解~~~~

代码如下：

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

const int N = 200002;
char str[N];
int  next[N];

void get_next(int len)
{
    int i = 0;
    int j = -1;
    next[i] = -1;
    while(i < len)
    {
        if(j == -1 || str[i] == str[j])
        {
            i++;
            j++;
            next[i] = j;
        }
        else
        {
            j = next[j];
        }
    }
}

int main()
{
    int t;
    int len;
    scanf("%d", &t);
    while(t--)
    {
        scanf("%d", &len);
        scanf("%s", str);
        get_next(len);
        int res = len + next[len];
        for(int i = 0; i < len; i++)
        {
            if(next[i] > 0 && next[i] + 1 != next[i + 1])
            {
                res += next[i];
            }
        }
        printf("%d\n", res % 10007);
    }
    return 0;
}