AcWing 1085 不要62 数位dp

#include <bits/stdc++.h>
using namespace std;

const int N = 35;

int f[N][10];

void init()
{
	for (int i = 0; i <= 9; i ++ ) if (i != 4) f[1][i] = 1;
	
	for (int i = 1; i < N; i ++ )
		for (int j = 0; j <= 9; j ++ )
		{
			if (j == 4) continue;
			for (int k = 0; k <= 9; k ++ )
			{
				if (k == 4 || (j == 6 && k == 2)) continue;
				f[i][j] += f[i - 1][k];
			}
		}
}

int dp(int n)
{
	if (!n) return 1;
	
	vector<int> nums;
	while (n) nums.push_back(n % 10), n /= 10;
	
	int res = 0, last = 0;
	for (int i = nums.size() - 1; i >= 0; i -- )
	{
		int x = nums[i];
		for (int j = 0; j < x; j ++ )	
		{
			if (j == 4 || last == 6 && j == 2) continue;
			res += f[i + 1][j];
		}
		
		if (x == 4 || last == 6 && x == 2) break;
		last = x;
		
		if (!i) res ++;
	}
	
	return res;
}

int main()
{
	init();
	
	int l, r;
	while (cin >> l >> r, l || r)
	{
		cout << dp(r) - dp(l - 1) << endl;
	}
}