#include <bits/stdc++.h> using namespace std; long long dp[20][11][11][2][2]; vector<int> num; long long calc(int pos, int pre1, int pre2, int f, int leading_0) { if (pos == num.size()) return 1; if (dp[pos][pre1][pre2][f][leading_0] != -1) return dp[pos][pre1][pre2][f][leading_0]; long long res = 0; int M = (f == 1 ? 9 : num[pos]); for (int i = 0; i <= M; i++) { int F = f; if (F == 0 && i < M) F = 1; if (leading_0) { if (i == pre1 || i == pre2) continue; res = res + calc(pos + 1, pre2, i, F, 1); } else { if (i == 0) res = res + calc(pos + 1, pre1, pre2, F, 0); else res = res + calc(pos + 1, pre1, i, F, 1); } } return dp[pos][pre1][pre2][f][leading_0] = res; } long long solve(long long x) { num.clear(); memset(dp, -1, sizeof dp); while (x > 0) { num.push_back(x % 10); x = x / 10; } reverse(num.begin(), num.end()); return calc(0, 10, 10, 0, 0); } int main() { long long a, b; cin >> a >> b; cout << solve(b) - solve(a - 1) + (a == 0 ? 1 : 0); return 0; }

numbers.cpp: In function 'long long int calc(int, int, int, int, int)':
numbers.cpp:8:13: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
    8 |     if (pos == num.size()) return 1;
      |         ~~~~^~~~~~~~~~~~~