BZOJ 1566: [NOI2009]管道取珠 另类DP

#include<cstdio>
#include<cstdlib>
#include<ctime>
#include<cmath>
#include<cstring>
#include<string>
#include<algorithm>
#include<iostream>
#include<iomanip>
using namespace std;
char s1[600];
char s2[600];
int f[502][502][502];
const int mod=1024523;
int main()
{
int n,m;
scanf("%d%d",&n,&m);
scanf("%s",s1+1);
scanf("%s",s2+1);
for(int i=1;i*2<=n;i++) swap(s1[i],s1[n-i+1]);
for(int j=1;j*2<=m;j++) swap(s2[j],s2[m-j+1]);
s1[n+1]='*';
s2[m+1]='^';
f[0][0][0]=1;
for(int i=0;i<=n+m;i++)
for(int j=0;j<=n && j<=i;j++)
for(int k=0;k<=n && k<=i;k++)
{
int o1=j;
int o2=i-j;
int t1=k;
int t2=i-k;
if(o2>m || t2>m) continue;
if(s1[o1+1]==s1[t1+1]) (f[o1+1][o2][t1+1]+=f[o1][o2][t1])%=mod;
if(s2[o2+1]==s2[t2+1]) (f[o1][o2+1][t1]+=f[o1][o2][t1])%=mod;
if(s1[o1+1]==s2[t2+1]) (f[o1+1][o2][t1]+=f[o1][o2][t1])%=mod;
if(s2[o2+1]==s1[t1+1]) (f[o1][o2+1][t1+1]+=f[o1][o2][t1])%=mod;
}
cout<<f
[m]
<<endl;
return 0;
}