Submission #102364

#	Time	Username	Problem	Language	Result	Execution time	Memory
102364		WLZ	Palindrome-Free Numbers (BOI13_numbers)	C++17	100 / 100	3 ms	512 KiB

numbers

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

long long dp[20][2][2][11][11];
vector<int> num;
int n;

long long solve(int i, int sm, int lz, int prev1, int prev2) {
  if (i == n) {
    return !lz;
  }
  if (dp[i][sm][lz][prev1][prev2] != -1) {
    return dp[i][sm][lz][prev1][prev2];
  }
  long long ans = 0;
  int mx;
  if (sm) {
    mx = num[i];
  } else {
    mx = 9;
  }
  for (int d = 0; d <= mx; d++) {
    if (d == prev1 || d == prev2) {
      continue;
    }
    if (lz && d == 0) {
      ans += solve(i + 1, (sm && d == num[i]), 1, 10, 10);
    } else {
      ans += solve(i + 1, (sm && d == num[i]), 0, prev2, d);
    }
  }
  return (dp[i][sm][lz][prev1][prev2] = ans);
}

long long calc(long long x) {
  num.clear();
  while (x > 0) {
    num.push_back(x % 10);
    x /= 10;
  }
  reverse(num.begin(), num.end());
  n = (int) num.size();
  memset(dp, -1, sizeof dp);
  return solve(0, 1, 1, 10, 10);
}

int main() {
  ios::sync_with_stdio(false);
  cin.tie(0);
  long long a, b;
  cin >> a >> b;
  long long ans = calc(b);
  if (a > 1) {
    ans -= calc(a - 1);
  }
  if (a == 0) {
    ans++;
  }
  cout << ans << '\n';
  return 0;
}

• Subtask 1: 25 / 25
• Subtask 2: 75 / 75