UESTC 250 windy数(数位DP)

#include <map>
#include <set>
#include <list>
#include <cmath>
#include <queue>
#include <stack>
#include <cstdio>
#include <vector>
#include <string>
#include <cctype>
#include <complex>
#include <cassert>
#include <utility>
#include <cstring>
#include <cstdlib>
#include <iostream>
#include <algorithm>
using namespace std;
typedef pair<int,int> PII;
typedef long long ll;
#define lson l,m,rt<<1
#define pi acos(-1.0)
#define rson m+1,r,rt<<11
#define All 1,N,1
#define read freopen("in.txt", "r", stdin)
const ll  INFll = 0x3f3f3f3f3f3f3f3fLL;
const int INF= 0x7ffffff;
const int mod =  1000000007;
int dp[15][15],a,b;
int bit[15],len;
//f表示前导0是否有效
int dfs(int i,int j,int f,int e){
if(i==0)
{
if(f)return 0;
else return 1;
}
if(!f&&!e&&dp[i][j]!=-1)return dp[i][j];
int l=e?bit[i]:9;
int num=0;
for(int v=0;v<=l;++v){
if(f){
if(v==0)
num+=dfs(i-1,v,1,e&&(v==l));
else
num+=dfs(i-1,v,0,e&&(v==l));
}
else if(abs(j-v)>=2)
num+=dfs(i-1,v,0,e&&(v==l));
}
if(!f&&!e)dp[i][j]=num;
return num;
}
int solve(ll x){
len=0;
while(x){
bit[++len]=x%10;
x/=10;
}
return dfs(len,0,1,1);
}
int main()
{
memset(dp,-1,sizeof(dp));
scanf("%d%d",&a,&b);
printf("%d\n",solve(b)-solve(a-1));
return 0;
}