Submission #755485

#	Time	Username	Problem	Language	Result	Execution time	Memory
755485		drdilyor	Palindrome-Free Numbers (BOI13_numbers)	C++17	100 / 100	7 ms	2452 KiB

numbers

	#include <bits/stdc++.h>

using namespace std;
using ll = long long;
const int inf = 1e9;
const ll infl = 1e18;

signed main() {
    cin.tie(0)->sync_with_stdio(0);
    string a, b;
    cin >> a >> b;
    string oa = a;

    vector<vector<vector<vector<vector<ll>>>>> memo;

    char null = '0';
    null--;

    auto dp = [&](auto& dp, string& s, int i, char prev, char cur, bool free, int start)->ll{
        if (i == (int)s.size()) return 1;
        int n = s.size();
        ll& key = memo[free][i][start][prev-null][cur-null];
        if (key != -1) return key;
        ll res = 0;
        for (char c = '0'; c <= '9'; c++) {
            if (c == prev && start <= i-2) continue;
            if (c == cur && start <= i-1) continue;
            if (free || c <= s[i]) {
                res += dp(dp, s, i+1, cur, c, free || c < s[i], start == n && c != '0' ? i : start);
            }
        }
        return key = res;
    };

    auto calc = [&](string s) {
        if (s == "0") return 1ll;
        memo = vector(2, vector(s.size(), vector(s.size()+1, vector(11, vector(11, -1ll)))));
        return dp(dp, s, 0, null, null, false, s.size());
    };

    ll res = calc(b) - calc(a) + 1;

    for (int i = 1; i < (int)a.size(); i++){
        if (a[i] == a[i-1]) {res--; break; }
        if (i >1 && a[i] == a[i-2]) {res--; break; }
    }
    cout << res << '\n';



    return 0;
}

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