Submission #637456

#	Time	Username	Problem	Language	Result	Execution time	Memory
637456		glome	Palindrome-Free Numbers (BOI13_numbers)	C++17	100 / 100	1 ms	388 KiB

numbers

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

long long dp[19][11][11][2][2];

string num;

long long rec(int pos, int prev1, int prev2, int f, int prev) {
    if(pos == num.size()) return 1;

    if(dp[pos][prev1][prev2][prev][f] != -1) return dp[pos][prev1][prev2][prev][f];
    
    int LIM = 9;
    if(!f) LIM = num[pos] - '0';
    
    long long res = 0;

    for (int i = 0; i<=LIM; i++) {
        if(prev) {
            if(i == prev2 || i == prev1) continue;
            res += rec(pos + 1, i, prev1, (f || i < LIM), prev);
        }
        else {
            res += rec(pos + 1, (i != 0 ? i : 10), prev1, (f || i < LIM), (i != 0));
        }
    }
    return dp[pos][prev1][prev2][f][prev] = res;


}

int main() {
    ios::sync_with_stdio(false);
    cin.tie(0);
    long long a,b, k = 0;
    cin >> a >> b;
    if(a == 0) k += 1;
    memset(dp, -1, sizeof(dp)); num = to_string(b);
    b = rec(0, 10, 10, 0, 0);
    a = max(a-1, 0LL);
    memset(dp, -1, sizeof(dp)); num = to_string(a);

    cout << b - rec(0, 10, 10, 0, 0) + k << '\n';
    return 0;
}

Compilation message (stderr)

numbers.cpp: In function 'long long int rec(int, int, int, int, int)':
numbers.cpp:10:12: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   10 |     if(pos == num.size()) return 1;
      |        ~~~~^~~~~~~~~~~~~

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