【DP】good bye 2015 D

#include<iostream>
#include<cstdio>
#include<cstring>
#include<cmath>
#include<cstdlib>
#include<algorithm>
using namespace std;
int f[5002][5002];
int n;
int lcp[5002][5002];
char s[100100];
int main()
{
int start1,start2;
char ch;
bool flag;
memset(f,0,sizeof(f));
f[0][0]=1;
scanf("%d ",&n);
for (int i=1;i<=n;i++)
scanf("%c",&s[i]);
for (int i=n;i;i--)
for (int j=i-1;j;j--)
lcp[i][j]=(s[i]==s[j]?lcp[i+1][j+1]+1:0);
for (int i=1;i<=n;i++)
for (int j=1;j<=i;j++)
{
start1=i-j+1;
start2=i-2*j+1;
f[i][j]=f[i][j-1];
if (s[start1]=='0') continue;
if (start2<=0) f[i][j]=(f[i][j]+f[start1-1][start1-1])%1000000007;
if (s[start2]=='0') {f[i][j]=(f[i][j]+f[start1-1][j-1])%1000000007;continue;}
if (lcp[start1][start2]>=j) f[i][j]=(f[i][j]+f[start1-1][j-1])%1000000007;
else
{
if (s[start1+lcp[start1][start2]]>s[start2+lcp[start1][start2]])
f[i][j]=(f[i][j]+f[start1-1][j])%1000000007;
else
f[i][j]=(f[i][j]+f[start1-1][j-1])%1000000007;
}
}
printf("%d",f

);
return 0;
}