Submission #1102884

#	Time	Username	Problem	Language	Result	Execution time	Memory
1102884		Avocabo	Palindrome-Free Numbers (BOI13_numbers)	C++17	72.50 / 100	2 ms	848 KiB

numbers

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

#define task "PALINFREE"
#define fi first
#define se second
#define pii pair <int, int>
#define pb push_back
#define ll long long 
#define pip pair <int, pii>
#define pli pair <ll, int>

const int N = 1e5 + 5;
const int mod = 1e9 + 7;
const ll inf = 1e18 + 7;

long long a, b, f[25][5][5][15][15];
int n;
string s;

int myabs(int x)
{
    return x < 0 ? -x : x;
}

void inp()
{
    cin >> a;
    cin >> b;
}

long long dp(int k, int st, int small, int pre1, int pre2)
{
    if (k == n)
        return 1;
    if (f[k][st][small][pre1][pre2] != -1)
        return f[k][st][small][pre1][pre2];
    long long ans = 0;
    int lim = 9;
    if (small)
        lim = s[k] - '0';
    //cout << s[k] << " " << lim << endl;
    for (int i=0; i<=lim; ++i)
    {
        if (i == pre1 || i == pre2)
            continue;
        int new_small = (small && i == lim);
        int new_start = (st || i != 0);
        if (new_start)
            ans += dp(k + 1, new_start, new_small, i, pre1);
        else ans += dp(k + 1, new_start, new_small, 10, 10);
    }
    //cout << k << " " << st << " " << small << " " << pre1 << " " << pre2 << " " << ans << endl;
    return (f[k][st][small][pre1][pre2] = ans);
}

long long calc(long long a)
{
    for (int i=0; i<20; ++i)
        for (int j=0; j<2; ++j)
            for (int x=0; x<2; ++x)
                for (int y=0; y<11; ++y)
                    for (int z=0; z <11; ++z)
                        f[i][j][x][y][z] = -1;
    s = to_string(a);
    n = (int)s.size();
    //cout << s << " " << n << endl;
    return dp(0, 1, 1, 10, 10);
}

void solve()
{
    cout << calc(b) - calc(a-1) << endl;
}

int main()
{
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);
    if (fopen(task".inp", "r"))
    {
        freopen(task".inp", "r", stdin);
        freopen(task".out", "w", stdout);
    }
    inp();
    solve();
    return 0;
}

Compilation message (stderr)

numbers.cpp: In function 'int main()':
numbers.cpp:83:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   83 |         freopen(task".inp", "r", stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
numbers.cpp:84:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   84 |         freopen(task".out", "w", stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~

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