Submission #1295621

#	Time	Username	Problem	Language	Result	Execution time	Memory
1295621		bakhtiyarn	Palindrome-Free Numbers (BOI13_numbers)	C++20	17.08 / 100	1097 ms	700 KiB

numbers

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

void TLE() { TLE(); }
string a, b; 

int dfs(int i, bool big, bool lit, char last_1, char last_2){
  if(i == b.size()) return 1;
  
  if(big and lit){
    int rest = b.size()-i-1, eight = 1;
    while(rest--) eight *= 8;
    
    int res = 0;
    for(char j='0'; j<='9'; j++){
      if(j == last_1 or j == last_2) continue;
      res += eight;
    }
    return res;
  }
  
  if(lit){
    int res = 0;
    for(char j=a[i]+1; j<='9'; j++){
      if(j == last_1 or j == last_2) continue;
      res += dfs(i+1, true, true, last_2, j);
    }
    
    if(a[i] != last_2 and a[i] != last_1) res += dfs(i+1, false, true, last_2, a[i]);
    return res;
  }
  if(big){
    int res = 0;
    for(char j='0'; j<b[i]; j++){
      if(j == last_1 or j == last_2) continue;
      res += dfs(i+1, true, true, last_2, j);
    }
    
    if(b[i] != last_2 and b[i] != last_1) res += dfs(i+1, true, false, last_2, b[i]);
    return res;
  }
  
  if(a[i] == b[i]) {
    if(last_1 == a[i] or last_2 == a[i]) {
      cout << 0;
      exit(0);
    }
    return dfs(i+1, false, false, last_2, a[i]);
  }
  
  int res = 0;
  for(char j=a[i]+1; j<b[i]; j++){
    if(j == last_1 or j == last_2) continue;
    res += dfs(i+1, true, true, last_2, j);
  }
    
  if(last_2 != a[i] and last_1 != a[i]) res += dfs(i+1, false, true, last_2, a[i]);
  if(last_2 != b[i] and last_1 != b[i]) res += dfs(i+1, true, false, last_2, b[i]);
  return res;
}

void solve(){
  int x, y; cin >> x >> y;
  int ans = 0;
  for(int i=x; i<=y; i++){
    string k = to_string(i);
    bool is = true;
    for(int j=1; j<k.size(); j++){
      if(k[j] == k[j-1]) is = false;
      if(j>1 and k[j] == k[j-2]) is = false;
    }
    if(is) ans++;
  }
  
  a = to_string(x);
  b = to_string(y);
  while(a.size() < b.size()) a = '0' + a;
  if(ans != dfs(0, false, false, '%', '&')) TLE();
  cout << dfs(0, false, false, '%', '&');
}

signed main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  solve();
}

• Subtask 1: 13.75 / 25
• Subtask 2: 3.3333 / 75