結果

問題 No.979 Longest Divisor Sequence
ユーザー fukafukatani
提出日時 2020-01-31 22:05:00
言語 Rust
(1.83.0 + proconio)
結果
AC  
実行時間 332 ms / 2,000 ms
コード長 2,818 bytes
コンパイル時間 13,430 ms
コンパイル使用メモリ 377,548 KB
実行使用メモリ 7,320 KB
最終ジャッジ日時 2024-09-17 08:19:52
合計ジャッジ時間 14,767 ms
ジャッジサーバーID
（参考情報） 		judge2 / judge4
このコードへのチャレンジ
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ファイルパターン 結果
other AC * 16
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ソースコード

diff # 

#![allow(unused_imports)]
#![allow(non_snake_case)]
use std::cmp::*;
use std::collections::*;
use std::io::Write;

#[allow(unused_macros)]
macro_rules! debug {
    ($($e:expr),*) => {
        #[cfg(debug_assertions)]
        $({
            let (e, mut err) = (stringify!($e), std::io::stderr());
            writeln!(err, "{} = {:?}", e, $e).unwrap()
        })*
    };
}

fn get_primes(n: i64) -> Vec<i64> {
    let mut is_prime = vec![true; n as usize + 1];
    let mut primes = Vec::new();
    is_prime[0] = false;
    is_prime[1] = false;

    for i in 2..n + 1 {
        if is_prime[i as usize] {
            primes.push(i);
            let mut j = 2 * i;
            while j < n {
                is_prime[j as usize] = false;
                j += i;
            }
        }
    }
    primes
}

fn factorize(mut num: i64, primes: &Vec<i64>) -> std::collections::HashMap<i64, i64> {
    // max_primes >= (num)^(1/2)
    let mut dict = std::collections::HashMap::new();
    for &p in primes.iter() {
        while num % p == 0 {
            *dict.entry(p).or_insert(0) += 1;
            num /= p;
        }
        if num == 1 {
            break;
        }
    }
    if num != 1 {
        dict.insert(num, 1);
    }
    dict
}

fn collect_all_factors(dict: &std::collections::HashMap<i64, i64>) -> Vec<i64> {
    let mut ret = vec![1];
    for &key in dict.keys() {
        let mut new = ret.clone();

        for coef in 1..dict[&key] + 1 {
            let coef_1 = pow(key, coef);
            for &num in ret.iter() {
                new.push(num * coef_1);
            }
        }
        ret = new;
    }
    ret
}

fn pow(n: i64, mut p: i64) -> i64 {
    let mut r = n;
    let mut ret = 1;
    while p > 0 {
        if p % 2 == 0 {
            r = r * r;
            p /= 2;
        } else {
            ret = ret * r;
            p -= 1;
        }
    }
    ret
}

fn main() {
    let n = read::<usize>();
    let a = read_vec::<i64>();
    let a_max = *a.iter().max().unwrap();
    let mut i = 0;
    while i * i <= a_max {
        i += 1;
    }
    let primes = get_primes(i as i64);

    let mut dp = vec![0; a_max as usize + 1];
    dp[a[0] as usize] = 1;
    for i in 1..n {
        let dict = factorize(a[i] as i64, &primes);
        for num in collect_all_factors(&dict) {
            if num == a[i] {
                continue;
            }
            dp[a[i] as usize] = max(dp[a[i] as usize], dp[num as usize] + 1);
        }
    }
    println!("{}", dp.iter().max().unwrap());
}

fn read<T: std::str::FromStr>() -> T {
    let mut s = String::new();
    std::io::stdin().read_line(&mut s).ok();
    s.trim().parse().ok().unwrap()
}

fn read_vec<T: std::str::FromStr>() -> Vec<T> {
    read::<String>()
        .split_whitespace()
        .map(|e| e.parse().ok().unwrap())
        .collect()
}
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