Submission #579881

#	Time	Username	Problem	Language	Result	Execution time	Memory
579881		RealSnake	Palindrome-Free Numbers (BOI13_numbers)	C++14	72.50 / 100	1 ms	340 KiB

numbers

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

#define ll long long
#define mod 1000000007

#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
using namespace __gnu_pbds;
typedef tree<ll, null_type, less<ll>, rb_tree_tag, tree_order_statistics_node_update> ordered_set;

ll n;
string s;
ll dp[20][2][11][11];

ll solve(ll ind, bool b, ll lst1, ll lst2) {
    if(ind + 1 == n)
        return 1;
    if(dp[ind + 1][b][lst1][lst2])
        return dp[ind + 1][b][lst1][lst2];
    ll ans = 0;
    if(b == 1) {
        ll d = (s[ind + 1] - '0');
        for(ll i = 0; i <= d; i++) {
            if(i == lst1 || i == lst2)
                continue;
            ans += solve(ind + 1, (i == d), i, lst1);
        }
    }
    else {
        for(ll i = 0; i <= 9; i++) {
            if(i == lst1 || i == lst2)
                continue;
            ans += solve(ind + 1, 0, i, lst1);
        }
    }
    return dp[ind + 1][b][lst1][lst2] = ans;
}

signed main() {

    ios::sync_with_stdio(false);
    cin.tie(NULL);
    cout.tie(NULL);

    string b;
    ll a;
    cin >> a >> b;
    s = b;
    n = s.size();
    ll ans = solve(-1, 1, 10, 10);
    a--;
    if(a >= 0) {
        memset(dp, 0, sizeof dp);
        s = to_string(a);
        n = s.size();
        ans -= solve(-1, 1, 10, 10);
    }
    cout << ans;

    return 0;
}

• Subtask 1: 12.5 / 25
• Subtask 2: 60 / 75