Submission #1015939

#	Time	Username	Problem	Language	Result	Execution time	Memory
1015939		caterpillow	Palindrome-Free Numbers (BOI13_numbers)	C++17	100 / 100	2 ms	600 KiB

numbers

#include <bits/stdc++.h>

using namespace std;

using ll = long long;
using pl = pair<ll, ll>;
using pi = pair<int, int>;
#define vt vector
#define f first
#define s second
#define pb push_back
#define all(x) x.begin(), x.end() 
#define size(x) ((int) (x).size())
#define FOR(i, a, b) for (int i = (a); i < (b); i++)
#define ROF(i, a, b) for (int i = (b) - 1; i >= (a); i--)
#define F0R(i, b) FOR (i, 0, b)
#define endl '\n'
const ll INF = 1e18;
const int inf = 1e9;

template<template<typename> class Container, typename T>
ostream& operator<<(ostream& os, Container<T> o) {
    os << "{"; 
    int g = size(o); 
    for (auto i : o) os << i << ((--g) == 0 ? "" : ", "); 
    os << "}";
    return os;
}

void _print() {
    cerr << "\n";
}

template<typename T, typename ...V>
void _print(T t, V... v) {
    cerr << t; if (sizeof...(v)) cerr << ", "; _print(v...);
}

#ifdef LOCAL
#define dbg(x...) cerr << #x << " = "; _print(x);
#else
#define dbg(x...)
#define cerr if (0) std::cerr
#endif

/*

we just need to remember the last and second digits

*/

using t4 = tuple<int, int, int, int>;
map<t4, ll> memo;
vt<ll> digs;

// which are we placing
ll dp(int i, int last, int second_last, int tight) {
    if (i == -1) return 1;
    auto it = memo.find({i, last, second_last, tight});
    if (it != memo.end()) return it->s;

    int has_not_placed_digit = last >= 10;

    ll ans = 0;
    if (tight) {
        F0R (j, digs[i] + 1) {
            if (j == last || j == second_last) continue;
            ans += dp(i - 1, j + (has_not_placed_digit && j == 0 ? 10 : 0), last, j == digs[i]);
        }
    } else {
        F0R (j, 10) {
            if (j == last || j == second_last) continue;
            ans += dp(i - 1, j + (has_not_placed_digit && j == 0 ? 10 : 0), last, 0);
        }
    }
    return memo[{i, last, second_last, tight}] = ans;
}

ll count(ll x) {
    if (x < 0) return 0;
    digs.clear();
    memo.clear();
    while (x) digs.pb(x % 10), x /= 10;
    return dp(size(digs) - 1, 10, 10, 1);
}

main() {
    cin.tie(0)->sync_with_stdio(0);
    
    ll a, b; cin >> a >> b;
    cout << count(b) - count(a - 1) << endl;
}

Compilation message (stderr)

numbers.cpp:87:1: warning: ISO C++ forbids declaration of 'main' with no type [-Wreturn-type]
   87 | main() {
      | ^~~~

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