odd-even number

#pragma comment(linker, "/STACK:1024000000,1024000000")#include<iostream>#include<cstdio>#include<cmath>#include<string>#include<queue>#include<algorithm>#include<stack>#include<cstring>#include<vector>#include<list>#include<set>#include<map>using namespace std;#define ll long long#define pi (4*atan(1.0))#define eps 1e-4#define bug(x)  cout<<"bug"<<x<<endl;const int N=2e3+10,M=9e3+10,inf=2147483647,mod=1e9+7;const ll INF=1e18+10;ll f[20][3][20][3],bit[20];ll dp(int pos,int pre,int now,int k,int flag,int p){    //cout<<pos<<" "<<pre<<" "<<now<<" "<<k<<endl;    if(pos==0)return (pre%2!=now%2&&k==0);    if(flag&&f[pos][pre][now][k]!=-1)return f[pos][pre][now][k];    int x=flag?9:bit[pos];    ll ans=0;    for(int i=0;i<=x;i++)    {        if(!p&&!i)            ans+=dp(pos-1,1,0,0,flag||i<x,p||i);        else        {            if(pre%2==i%2)                ans+=dp(pos-1,i%2,now+1,k,flag||i<x,p||i);            else            {                if(now%2!=pre%2)                    ans+=dp(pos-1,i%2,1,k,flag||i<x,p||i);                else                    ans+=dp(pos-1,i%2,1,1,flag||i<x,p||i);            }        }    }    if(flag)f[pos][pre][now][k]=ans;    return ans;}ll getans(ll x){    int len=0;    while(x)    {        bit[++len]=x%10;        x/=10;    }    return dp(len,1,0,0,0,0);}int main(){    int T,cas=1;    memset(f,-1,sizeof(f));    scanf("%d",&T);    while(T--)    {        ll l,r;        scanf("%lld%lld",&l,&r);        printf("Case #%d: %lld\n",cas++,getans(r)-getans(l-1));    }    return 0;}