SPOJ Number of Palindromes(回文树)

#include <iostream>
#include <string.h>
#include <stdlib.h>
#include <algorithm>
#include <math.h>
#include <stdio.h>

using namespace std;
#define MAX 1005
struct Node
{
    int next[26];
    int len;
    int sufflink;
    int num;
}tree[MAX];
char s[MAX];

int num;
int suff;
bool addLetter(int pos)
{
    int cur=suff,curlen=0;
    int let=s[pos]-'a';

    while(1)
    {
        curlen=tree[cur].len;
        if(pos-1-curlen>=0&&s[pos-1-curlen]==s[pos])
            break;
        cur=tree[cur].sufflink;
    }
    if(tree[cur].next[let])
    {
        suff=tree[cur].next[let];
        return false;
    }
    num++;
    suff=num;
    tree[num].len=tree[cur].len+2;
    tree[cur].next[let]=num;
    if(tree[num].len==1)
    {
        tree[num].sufflink=2;
        tree[num].num=1;
        return true;
    }
    while(1)
    {
        cur=tree[cur].sufflink;
        curlen=tree[cur].len;
        if(pos-1-curlen>=0&&s[pos-1-curlen]==s[pos])
        {
            tree[num].sufflink=tree[cur].next[let];
            break;
        }
    }
    tree[num].num=1+tree[tree[num].sufflink].num;
    return true;

}
void initTree()
{
    num=2;suff=2;
    tree[1].len=-1;tree[1].sufflink=1;
    tree[2].len=0;tree[2].sufflink=1;
}
int main()
{
    scanf("%s",s);
    int len=strlen(s);
    initTree();
    long long int ans=0;
    for(int i=0;i<len;i++)
    {
         addLetter(i);
         ans+=tree[suff].num;
    }
    printf("%d\n",ans);
    return 0;
}