数位DP
传送门【一本通提高数位动态规划】windy数
![](https://images.cnblogs.com/OutliningIndicators/ContractedBlock.gif)
#include<bits/stdc++.h> using namespace std; #define ll long long ll dp[15][15],ans; bool vis[15][15]; ll a[15]; ll l,r,len; ll dfs(ll pos,ll pre,ll zero,ll limit) { if(pos>len)return 1; if(!limit&&vis[pos][pre])return dp[pos][pre]; ll res=limit?a[len-pos+1]:9,ret=0; for(int i=0;i<=res;i++) { if(abs(i-pre)<2) continue; if(zero&&i==0) ret+=dfs(pos+1,-2,1,limit&&i==res); else ret+=dfs(pos+1,i,0,limit&&i==res); } if((!limit)&&(!zero))dp[pos][pre]=ret; vis[pos][pre]=1; return ret; } inline void get(ll x) { len=0; while(x)a[++len]=x%10,x/=10; } int main() { scanf("%lld%lld",&l,&r); get(r); ll ans=dfs(1,-2,1,1); memset(dp,0,sizeof dp); memset(vis,0,sizeof vis); get(l-1); ll ans1=dfs(1,-2,1,1); printf("%lld",ans-ans1); }