请问这份代码哪里有问题?

#include<bits/stdc++.h>
using namespace std;
const int MAXN=50020;
int n,m,tot;
long long ans;
char c[MAXN],d[MAXN];
struct PAM
{
	int cnt,last;
	int sum[MAXN];
	int son[MAXN][28];
	int len[MAXN];
	int fail[MAXN];
	int t[MAXN];
	int new_node(int u)
	{
		len[++cnt]=u;
		return cnt;
	}
	int get_fail(int pre,int now,char *s)
	{
		while (s[now-len[pre]-1]!=s[now])
			pre=fail[pre];
		return pre;
	}
	void init()
	{
		cnt=1,last=0;
		len[0]=0,len[1]=-1;
		fail[0]=1;
		fail[1]=1;
	}
	void insert(char ch,int k,char *s)
	{
		int cur=get_fail(last,k,s);
		if (!son[cur][ch-'a'])
		{
			int now=new_node(len[cur]+2);
			fail[now]=son[get_fail(fail[cur],k,s)][ch-'a'];
			son[cur][ch-'a']=now;
		}
		last=son[cur][ch-'a'];
		t[last]++;
	}
}p1,p2;
void dfs(int l,int r)
{
	if ((l+r)>2) ans+=1ll*p1.t[l]*p2.t[r];
	for (int i=0;i<26;i++)
	if (p1.son[l][i]&&p2.son[r][i]) dfs(p1.son[l][i],p2.son[r][i]);
}
int main()
{
	scanf("%s%s",c+1,d+1);
	n=strlen(c+1);m=strlen(d+1);
	p1.init(),p2.init();
	for (int i=1;i<=n;i++) p1.insert(c[i],i,c);
	for (int i=1;i<=m;i++) p2.insert(d[i],i,d);
	for (int i=p1.cnt;i;i--) p1.t[p1.fail[i]]+=p1.t[i];
	for (int i=p2.cnt;i;i--) p2.t[p2.fail[i]]+=p2.t[i];
	dfs(1,1);dfs(0,0);
	printf("%lld\n",ans);
	return 0;
}