windy数(数位dp)

#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
const int N = 34;
int f[N][10];//第i位取j的windy数 max
ll l, r;
void init() {
  for (int i = 0; i <= 9; i++) f[1][i] = 1;
  for (int i = 2; i <= N; i++) {
    for (int j = 0; j <= 9; j++) {
      for (int k = j - 2; k >= 0; k--)
        f[i][j] += f[i - 1][k];
      for (int k = j + 2; k <= 9; k++)
        f[i][j] += f[i - 1][k];
    }
  }
}
ll cal(ll n) {
  if (!n) return 0;
  vector<ll>num;
  while (n) num.push_back(n % 10), n /= 10;
  ll res = 0;
  ll last = -1;
  for (int i = num.size() - 1; i >= 0; i--) {
    int x = num[i];
    for(int j = (i == num.size() - 1) ? 1 : 0;j < x;++j){
  //只要与上一个数的差值大于2，就是合法的windy数
            if(abs(j - last) >= 2)res += f[i + 1][j];
        }
    if ((x <= last + 1 && x >= last - 1)) break;
    last = x;
    if (!i) res++;
  }
  //包含前导零情况
  for(int i = 1;i <= num.size() - 1;++i){
        for(int j = 1;j <= 9;++j){
            res += f[i][j];
        }
    }
  return res;
}
int main() {
  init();
//  for (int i = 1; i <= 3; i++) {
//    for (int j = 0; j <= 9; j++) {
//      printf("f%d%d=%d ", i, j, f[i][j]);
//    }
//    cout << endl;
//  }
    cin>>l>>r;
  cout << cal(r) - cal(l - 1) << endl;
  return 0;
}
/*
25 50
*/