HDU 3336 Count the string / KMP

#include <cstdio>
#include <cstring>
const int maxn = 200010;
const int mod = 10007;
char a[maxn];
int f[maxn];
int dp[maxn];
int n, m;

void getFail()
{
	f[0] = f[1] = 0;
	for(int i = 1; i < n; i++)
	{
		int j = f[i];
		while(j && a[i] != a[j])
			j = f[j];
		f[i+1] = a[i] == a[j] ? j+1 : 0;
	}
	dp[0] = 0;
	for(int i = 1; i <= n; i++)
	{
		dp[i] = dp[f[i]]+1;
		m += dp[i];
		m %= mod;
	}
}
int main()
{
	int T;
	scanf("%d", &T);
	while(T--)
	{
		m = 0;
		scanf("%d %s", &n, a);
		getFail();
		printf("%d\n", m);
	}
	return 0;
}