Submission #1178978

#	Time	Username	Problem	Language	Result	Execution time	Memory
1178978		_dtq_	Palindrome-Free Numbers (BOI13_numbers)	C++20	32.50 / 100	1 ms	840 KiB

numbers

#include<bits/stdc++.h>
#define ll long long
#define fi first
#define se second
#define pb push_back
#define all(v) v.begin(), v.end()
#define sz(x) (long long)(x.size())
using namespace std;

ll a, b, maxn, t[30], dp[30][30][30][3];

ll calc( ll vt, ll x, ll y, bool c, ll sum )
{
    if(vt == 0)
        return dp[vt][x][y][c] = 1;

    if(dp[vt][x][y][c] != -1) return dp[vt][x][y][c];

    ll ans = 0;

    for( int w = 0; w <= (c ? t[vt] : 9); w ++ )
    {
        if(w == y && sum) continue;

        if(w == x && sum >= 10) continue;

        //cout << vt << " " << w << "\n";

        ans += calc(vt - 1, y, w, c & (w == t[vt]), sum * 10 + w);
    }

    return dp[vt][x][y][c] = ans;
}

ll solve( ll k )
{
    memset(dp, -1, sizeof(dp));

    string s;

    while(k)
    {
        s = s + char(k % 10 + 48);

        k /= 10;
    }

    for( int w = 0; w < sz(s); w ++ )
    {
        t[w + 1] = s[w] - 48;

        maxn = w + 1;
    }

    return calc( maxn, 20, 20, 1, 0 );
}
int main()
{
    cin.tie(0)->sync_with_stdio(0);

    cin >> a >> b;

    if( a == 0 )
    {
        cout << solve(b);

        return 0;
    }

    cout << solve(b) - solve(a - 1);

    return 0;
}

• Subtask 1: 12.5 / 25
• Subtask 2: 20 / 75