Submission #547252

#	Time	Username	Problem	Language	Result	Execution time	Memory
547252		Jomnoi	Palindrome-Free Numbers (BOI13_numbers)	C++17	100 / 100	2 ms	392 KiB

numbers

#include <bits/stdc++.h>
#define DEBUG 0
using namespace std;

long long dp[20][2][2][11][11];

long long solve2(string s, int idx = 0, bool f = false, bool lead0 = true, int p1 = 10, int p2 = 10) {
    if(dp[idx][f][lead0][p1][p2] != -1) {
        return dp[idx][f][lead0][p1][p2];
    }
    if(idx == s.size()) {
        return 1;
    }

    int len = 9;
    if(f == false) {
        len = s[idx] - '0';
    }

    long long res = 0;
    for(int i = 0; i <= len; i++) {
        if(i == p1 or i == p2) {
            continue;
        }

        bool nf = f, nlead0 = lead0;
        int np1 = i, np2 = p1;
        if(i < len) {
            nf = true;
        }
        if(i != 0) {
            nlead0 = false;
        }
        if(nlead0 == true) {
            np1 = np2 = 10;
        }
        res += solve2(s, idx + 1, nf, nlead0, np1, np2);
    }
    return dp[idx][f][lead0][p1][p2] = res;
}

long long solve(long long a) {
    for(int i = 0; i < 20; i++) {
        for(int j = 0; j <= 10; j++) {
            for(int k = 0; k <= 10; k++) {
                dp[i][0][0][j][k] = dp[i][1][0][j][k] = -1;
                dp[i][0][1][j][k] = dp[i][1][1][j][k] = -1;
            }
        }
    }

    string t;
    while(a > 0) {
        t.push_back(a % 10 + '0');
        a /= 10;
    }
    reverse(t.begin(), t.end());

    return solve2(t);
}

int main() {
    cin.tie(0)->sync_with_stdio(0);
    long long a, b, ans;
    cin >> a >> b;
    ans = solve(b);
    if(a > 0) {
        ans -= solve(a - 1);
    }
    cout << ans;
    return 0;
}

Compilation message (stderr)

numbers.cpp: In function 'long long int solve2(std::string, int, bool, bool, int, int)':
numbers.cpp:11:12: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   11 |     if(idx == s.size()) {
      |        ~~~~^~~~~~~~~~~

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