Submission #1213036

#	Time	Username	Problem	Language	Result	Execution time	Memory
1213036		i_love_spring	Palindrome-Free Numbers (BOI13_numbers)	C++20	100 / 100	2 ms	1356 KiB

numbers

#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define ar array
ll dp[20][12][12][12][2][2];
string s;
bool has_pal(int a,int b,int c) {
  if (a != -1 && b != -1 && a == b) return true;
  if (a != -1 && c != -1 && a == c) return true;
  if (b != -1 && c != -1 && b == c) return true;
  return false; 
}
ll get(int pos,int a,int b,int c,bool tight,bool zero) {
  if (pos == s.size()) return 1;
  ll& res = dp[pos][a + 1][b + 1][c + 1][tight][zero];
  if (res != -1) {
    return res;
  } 
  res = 0;
  int limit = (tight ? s[pos] - '0' : 9);
  for (int d = 0; d <= limit;d++) {
    int na = b,nb = c,nc = d;
    bool new_zero = zero && (d == 0);
    bool new_tight = tight && (d == limit);
    if (new_zero) {
      na = -1 , nb = -1 , nc = -1;
    }
    if (!new_zero && has_pal(na,nb,nc)) continue;
    res += get(pos + 1,na,nb,nc,new_tight,new_zero);
  }
  return res;
} 
ll get(ll y) {
  s = to_string(y);
  memset(dp,-1,sizeof(dp));
  return get(0,-1,-1,-1,true,true);
}
void solve() {  
  ll x,y;
  cin >> x >> y;
  cout << get(y) - get(x - 1);
}
signed main() {
  ios_base::sync_with_stdio(false);
  cin.tie(nullptr);
  cout.tie(nullptr);
  int t = 1;
  //cin >> t;
  while (t--) {
    solve();
    cout << "\n";
  }
  return 0;
} 

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