Submission #1311092

#	Time	Username	Problem	Language	Result	Execution time	Memory
1311092		chithanhnguyen	Palindrome-Free Numbers (BOI13_numbers)	C++20	72.50 / 100	2 ms	592 KiB

numbers

/*
Author: Nguyen Chi Thanh - High School for the Gifted - VNU.HCM (i2528)
*/
#include <bits/stdc++.h>
using namespace std;

// #define int long long
#define ull unsigned long long
#define ld long double
#define pii pair<int, int>
#define fi first
#define se second
#define __builtin_popcount __builtin_popcountll
#define all(x) (x).begin(), (x).end()
#define BIT(x, i) (((x) >> (i)) & 1)
#define MASK(x) ((1ll << (x)))

#define debug(a, l, r) for (int _i = (l); _i <= (r); ++_i) cout << (a)[_i] << ' '; cout << '\n';

int n;
string A, B;
long long dp[22][2][2][15][15][2];

long long F(int i, int left, int right, int pre, int pre2, int leading) {
    if (i == n + 1) return 1;
    
    long long &memo = dp[i][left][right][pre + 1][pre2 + 1][leading];
    if (memo != -1) return memo;

    memo = 0;
    int lo = (left ? 0 : A[i] - '0');
    int hi = (right ? 9 : B[i] - '0');

    for (int c = lo; c <= hi; ++c) {
        int nxt_left = (left | (c > A[i] - '0'));
        int nxt_right = (right | (c < B[i] - '0'));
        int nxt_leading = leading & (c == 0);

        if (c == pre || c == pre2) continue;

        memo += F(i + 1, nxt_left, nxt_right, nxt_leading ? -1 : c, pre, nxt_leading);
    }

    return memo;
}

long long G(long long a, long long b) {
    assert(a <= b);
    A = to_string(a);
    B = to_string(b);
    n = (int)A.size();

    while (A.size() < B.size()) A = '0' + A;
    A = ' ' + A; B = ' ' + B;

    memset(dp, -1, sizeof dp);
    return F(1, 0, 0, -1, -1, 1);
}

void solve() {
    long long a, b; cin >> a >> b;
    cout << G(a, b);
}

signed main() {
    #ifdef NCTHANH
    freopen("input.txt", "r", stdin);
    freopen("output.txt", "w", stdout);
    #endif
    ios_base::sync_with_stdio(0);
    cin.tie(nullptr); cout.tie(nullptr);

    solve();

    return 0;
}

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