제출 #107973

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
107973		bestin_1	Palindrome-Free Numbers (BOI13_numbers)	C++17	96.25 / 100	4 ms	512 KiB

numbers

#include <iostream>
#include <random>
#include <chrono>
#include <algorithm>
#include <cstring>

#define rep(i, x) for(int i = 0; i < x; i++)
using namespace std;
typedef long long ll;
ll MOD = (ll)1e9 + 7;
const int N = 1e5+5, inf = 1e9+5;
ll add(ll x, ll y) { x += y; if (x >= MOD) return x - MOD; return x; }
ll sub(ll x, ll y) { x -= y; if (x < 0) return x + MOD; return x; }
ll mult(ll x, ll y) { return (x * y) % MOD; }
mt19937_64 rng(chrono::steady_clock::now().time_since_epoch().count());

ll dp[20][2][11][11];
vector<int> num;
// function for [0, x]
ll f(int pos, bool less, int slast, int last) {
    if (pos == num.size()) return 1;
    if (dp[pos][less][slast][last] != -1) return dp[pos][less][slast][last];

    ll ans = 0;
    for (int digit = 0; digit <= 9; digit++) {
        if (!less && digit > num[pos]) break;
        if (slast == digit || last == digit) continue;
        // if last is a leading zero (i.e. a 10) then the current zero is also a leading zero.
        ans += f(pos+1, less || digit < num[pos], last, last == 10 && digit == 0 ? 10 : digit);
    }
    return dp[pos][less][slast][last] = ans;
}

int main() {
    ios_base::sync_with_stdio(false); cin.tie(nullptr);
    ll a, b; cin >> a >> b;
    while (b > 0) {
        num.push_back(b%10);
        b/=10;
    }
    reverse(begin(num), end(num));
    memset(dp, -1, sizeof(dp));
    ll b_ans = f(0, false, 10, 10); // 10 is leading zero

    num.clear();
    a--;
    while (a > 0) {
        num.push_back(a%10);
        a/=10;
    }
    reverse(begin(num), end(num));
    memset(dp, -1, sizeof(dp));
    ll a_ans = f(0, false, 10, 10); // 10 is leading zero

    cout << b_ans-a_ans << endl;

}

컴파일 시 표준 에러 (stderr) 메시지

numbers.cpp: In function 'll f(int, bool, int, int)':
numbers.cpp:21:13: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     if (pos == num.size()) return 1;
         ~~~~^~~~~~~~~~~~~

• Subtask 1: 21.25 / 25
• Subtask 2: 75 / 75