[SCOI 2009]windy数

#include<bits/stdc++.h>
#define re return
#define reg register 
#define ll long long
#define inc(i,l,r) for(int i=l;i<=r;++i)
#define dec(i,l,r) for(int i=l;i>=r;--i)

using namespace std;
ll l,r,f[40][15],num[20];

ll dfs(int pos,int limit,int lead,int last)
{
    
    if(!lead)last=11;
    if(!pos)re 1;
    if(!limit&&(~f[pos][last]))    re f[pos][last];
    
    ll up=limit?num[pos]:9,res=0;
    
    inc(i,0,up)
    if(abs(last-i)>1)res+=dfs(pos-1,limit&&(i==up),lead||i,i);
    
    if(!limit)f[pos][last]=res;
    
    re res;
}

ll cala(int x)
{
    int len=0;
    while(x){
        num[++len]=x%10;
        x/=10;
    }
    re dfs(len,1,0,0);
}

int main()
{
    memset(f,-1,sizeof f);
    scanf("%lld%lld",&l,&r);
    printf("%lld\n",cala(r)-cala(l-1));
    re 0;
} 

 

一堆dfs乱搞+记忆化