Submission #778938

#	Time	Username	Problem	Language	Result	Execution time	Memory
778938		ind1v	Palindrome-Free Numbers (BOI13_numbers)	C++11	100 / 100	1 ms	340 KiB

numbers

#include <bits/stdc++.h>

using namespace std;

long long a, b;
vector<int> d;
long long f[20][10][10][2][2][2];

long long dp(int pos, int nprv, int prv, bool nz, bool nnz, bool t) {
  if (pos == d.size()) {
    return 1;
  }
  long long &res = f[pos][nprv][prv][nz][nnz][t];
  if (res != -1) {
    return res;
  }
  res = 0;
  int lim = t ? 9 : d[pos];
  for (int i = 0; i <= lim; i++) {
    if (nz && i == prv) {
      continue;
    }
    if (nnz && i == nprv) {
      continue;
    }
    res += dp(pos + 1, prv, i, nz || (i != 0), nz, t || (i < d[pos]));
  }
  return res;
}

long long solve(long long x) {
  if (x < 0) {
    return 0;
  }
  d.clear();
  while (x > 0) {
    d.emplace_back(x % 10);
    x /= 10;
  }
  reverse(d.begin(), d.end());
  memset(f, -1, sizeof(f));
  return dp(0, 0, 0, 0, 0, 0);
}

int main() {
  ios::sync_with_stdio(false);
  cin.tie(0);
  cin >> a >> b;
  cout << solve(b) - solve(a - 1);
  return 0;
}

Compilation message (stderr)

numbers.cpp: In function 'long long int dp(int, int, int, bool, bool, bool)':
numbers.cpp:10:11: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   10 |   if (pos == d.size()) {
      |       ~~~~^~~~~~~~~~~

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