CSES - Datatähti 2025 alku - Results
Submission details
Task:Tikut
Sender:EmuBird
Submission time:2024-11-09 17:20:21 +0200
Language:Rust (2021)
Status:READY
Result:27
Feedback
groupverdictscore
#1ACCEPTED7
#2ACCEPTED8
#3ACCEPTED12
#40
#50
#60
Test results
testverdicttimegroup
#1ACCEPTED0.00 s1, 3, 4, 5, 6details
#2ACCEPTED0.00 s1, 4, 5, 6details
#3ACCEPTED0.00 s1, 4, 5, 6details
#4ACCEPTED0.00 s1, 4, 5, 6details
#5ACCEPTED0.01 s2, 5, 6details
#6ACCEPTED0.01 s2, 5, 6details
#7ACCEPTED0.00 s3, 5, 6details
#8ACCEPTED0.00 s3, 5, 6details
#9ACCEPTED0.00 s3, 5, 6details
#10ACCEPTED0.00 s3, 5, 6details
#11ACCEPTED0.00 s3, 5, 6details
#12ACCEPTED0.00 s4, 5, 6details
#130.00 s4, 5, 6details
#140.00 s4, 5, 6details
#150.00 s4, 5, 6details
#16ACCEPTED0.01 s5, 6details
#170.03 s5, 6details
#180.02 s5, 6details
#19ACCEPTED0.02 s5, 6details
#20--6details
#21--6details
#22--6details

Code

use std::{cmp, io};
use std::collections::{HashSet, VecDeque};

struct Stick {
    length: u32, // Original length. Shall never be modified.
    parts: Vec<u32> // Lengths of each part. Should always be in descending order.
}
fn main() {
    let stdin = io::stdin();

    let (n, m) = {
        let mut input: String = String::new();
        stdin.read_line(&mut input).unwrap();
        let mut iter = input.trim().split_whitespace().map(|x| x.parse::<u32>().unwrap());
        (iter.next().unwrap(), iter.next().unwrap())
    };

    let mut sticks: Vec<Stick> = {
        let mut input: String = String::new();
        stdin.read_line(&mut input).unwrap();
        input.trim().split_whitespace().map(|x| {
            let length = x.parse::<u32>().unwrap();
            Stick {
                length,
                parts: vec![length]
            }
        }).collect()
    };
    assert_eq!(sticks.len(), n as usize);

    sticks.sort_by(|a, b| b.length.cmp(&a.length));
    let mut min = (sticks.last().unwrap().length, sticks.len() - 1);
    let mut max_list: VecDeque<(u32, HashSet<usize>)> = { // VecDeque<(len, HashSet<indices>)>
        let mut max_list: VecDeque<(u32, HashSet<usize>)> = VecDeque::with_capacity(sticks.len());
        for i in 0..sticks.len() {
            let stick_max = sticks[i].parts[0];
            if !max_list.is_empty() && max_list[max_list.len() - 1].0 == stick_max {
                let last_index = max_list.len() - 1;
                max_list[last_index].1.insert(i);
            } else {
                max_list.push_back((stick_max, HashSet::from([i])));
            }
        }
        max_list
    };
    
    let mut answers = Vec::<u32>::with_capacity(m as usize);
    let mut k = 0;
    while k < m {
        let index: usize = {
            // Splitting a max length stick is usually a good idea.
            let max_value = max_list[0].0;
            let some_max_occurrence = *max_list[0].1.iter().next().unwrap();
            let (max_stick_split_min, max_stick_split_max) = get_extremes_after_next_cut(&sticks[some_max_occurrence]);
            if max_stick_split_min >= min.0 {
                some_max_occurrence
            } else {
                // If splitting the max stick would cause the min value to drop, check if something better could be done.
                let mut next_index = some_max_occurrence;
                let mut next_delta = {
                    let mut comparison_max = max_value;
                    if max_list[0].1.len() <= 1 && max_list.len() > 1 {
                        comparison_max = cmp::max(max_stick_split_max, max_list[1].0);
                    }
                    comparison_max - max_stick_split_min
                };

                for i in 0..sticks.len() {
                    if i == some_max_occurrence {
                        continue;
                    }
                    let (split_min, _) = get_extremes_after_next_cut(&sticks[i]);
                    let delta = max_value - cmp::min(min.0, split_min);
                    if delta < next_delta {
                        next_delta = delta;
                        next_index = i;
                    }
                    if delta == 0 {
                        break;
                    }
                }

                next_index
            }
        };

        let previous_part_count = sticks[index].parts.len() as u32;
        let denominator = previous_part_count + 1;
        let new_parts = divide_stick(sticks[index].length, denominator);
        assert!(new_parts[0] <= max_list[0].0);
        let old_parts = &sticks[index].parts;
        let required_cuts = new_parts.len() - old_parts.len();
        assert!(required_cuts <= 1);

        if required_cuts > 0 {
            // Change max if needed
            if new_parts[0] != old_parts[0] {
                // Add the maximum length of this stick to max_list after splitting.
                match max_list.binary_search_by_key(&-(new_parts[0] as i32), |pair| -(pair.0 as i32)) {
                    Ok(i) => {
                        max_list[i].1.insert(index);
                    }
                    Err(i) => {
                        max_list.insert(i, (new_parts[0], HashSet::from([index])));
                    }
                };

                // Remove the old maximum length of this stick from max_list prior to the split.
                match max_list.binary_search_by_key(&-(old_parts[0] as i32), |pair| -(pair.0 as i32)) {
                    Ok(i) => {
                        max_list[i].1.remove(&index);
                        if max_list[i].1.is_empty() {
                            max_list.remove(i);
                        }
                    }
                    Err(_) => {
                        panic!("Old maximum value {} of stick {} was not in max_list.", &old_parts[0], index);
                    }
                };
            }

            // Change min if needed
            if new_parts.last().unwrap() < &min.0 {
                min = (*new_parts.last().unwrap(), index);
            }

            sticks[index].parts = new_parts;
            let delta = max_list[0].0 - min.0;
            answers.push(delta);
            k += 1;

            {
                let mut calculated_max = *sticks.first().unwrap().parts.first().unwrap();
                let mut calculated_min = *sticks.last().unwrap().parts.last().unwrap();
                for stick in &sticks {
                    for part in &stick.parts {
                        if *part < calculated_min {
                            calculated_min = *part;
                        }
                        if *part > calculated_max {
                            calculated_max = *part;
                        }
                    }
                }
                assert_eq!(calculated_min, min.0);
                assert_eq!(calculated_max, max_list[0].0);
            }
        } else {
            assert_eq!(max_list[0].0, 1);
            assert_eq!(min.0, 1);
            break;
        }
    }

    let answers: Vec<String> = answers.iter().take(m as usize).map(|a| a.to_string()).collect();
    println!("{}", answers.join(" "))
}

/// Divides a stick of given length into `denominator` parts.
/// The returned Vec is in descending size order. max - min <= 1 inside the Vec.
fn divide_stick(length: u32, denominator: u32) -> Vec<u32> {
    let mut parts = Vec::with_capacity(denominator as usize);

    let div = length / denominator;
    if div > 0 {
        let mut extra = length % denominator;
        for _ in 0..denominator {
            if extra > 0 {
                extra -= 1;
                parts.push(div + 1);
            } else {
                parts.push(div);
                assert!(div > 0);
            }
        }
    } else {
        for _ in 0..length {
            parts.push(1);
        }
    }

    assert_eq!(parts.iter().sum::<u32>(), length);
    assert!(parts.iter().max().unwrap() - parts.iter().min().unwrap() <= 1);
    parts
}

/// (min, max)
fn get_extremes_after_next_cut(stick: &Stick) -> (u32, u32) {
    let denominator = stick.parts.len() as u32 + 1;
    let min = cmp::max(stick.length / denominator, 1);
    let max = min + if stick.length % denominator == 0 { 0 } else { 1 };
    (min, max)
}

Test details

Test 1

Group: 1, 3, 4, 5, 6

Verdict: ACCEPTED

input
1 1
6

correct output

user output
0

Test 2

Group: 1, 4, 5, 6

Verdict: ACCEPTED

input
5 10
4 8 6 2 7

correct output
5 4 2 2 2 1 1 1 1 1 

user output
5 4 2 2 2 1 1 1 1 1

Test 3

Group: 1, 4, 5, 6

Verdict: ACCEPTED

input
5 10
5 5 8 6 7

correct output
3 3 2 3 2 2 1 1 1 2 

user output
3 3 2 3 2 2 1 1 1 2

Test 4

Group: 1, 4, 5, 6

Verdict: ACCEPTED

input
5 10
8 7 9 6 10

correct output
4 4 3 3 2 2 1 2 2 1 

user output
4 4 3 3 2 2 1 2 2 1

Test 5

Group: 2, 5, 6

Verdict: ACCEPTED

input
1000 1071
3 2 3 1 3 3 2 3 2 3 2 2 2 1 2 ...

correct output
2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 ...

user output
2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 ...

Test 6

Group: 2, 5, 6

Verdict: ACCEPTED

input
1000 1500
3 2 2 3 2 3 2 2 2 3 2 2 3 3 3 ...

correct output
2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 ...

user output
2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 ...

Test 7

Group: 3, 5, 6

Verdict: ACCEPTED

input
1000 2
15 710 210 347 398 66 318 277 ...

correct output
994 994 

user output
994 994

Test 8

Group: 3, 5, 6

Verdict: ACCEPTED

input
1000 2
743 890 592 942 736 969 616 50...

correct output
498 496 

user output
498 496

Test 9

Group: 3, 5, 6

Verdict: ACCEPTED

input
1000 2
987 968 920 994 988 918 914 95...

correct output
500 500 

user output
500 500

Test 10

Group: 3, 5, 6

Verdict: ACCEPTED

input
1000 2
996 1000 998 998 999 997 997 9...

correct output
500 500 

user output
500 500

Test 11

Group: 3, 5, 6

Verdict: ACCEPTED

input
1000 2
501 501 501 501 501 501 501 50...

correct output
1 168 

user output
1 168

Test 12

Group: 4, 5, 6

Verdict: ACCEPTED

input
100 200
145 136 74 83 73 36 196 115 11...

correct output
194 190 189 183 182 181 181 17...

user output
194 190 189 183 182 181 181 17...

Test 13

Group: 4, 5, 6

Verdict:

input
100 200
157 110 168 155 192 107 146 15...

correct output
95 96 96 95 93 94 94 94 90 91 ...

user output
95 96 96 95 93 94 94 94 90 91 ...

Test 14

Group: 4, 5, 6

Verdict:

input
50 200
137 118 160 118 146 160 140 18...

correct output
98 98 98 96 90 91 88 88 84 86 ...

user output
98 98 98 96 90 91 88 88 84 86 ...

Test 15

Group: 4, 5, 6

Verdict:

input
100 200
147 174 186 148 155 128 158 18...

correct output
99 99 98 98 97 97 96 96 95 95 ...

user output
99 99 98 98 97 97 96 96 95 95 ...

Test 16

Group: 5, 6

Verdict: ACCEPTED

input
1000 2000
928772177 816188227 216592201 ...

correct output
991676844 990940224 990685481 ...

user output
991676844 990940224 990685481 ...

Test 17

Group: 5, 6

Verdict:

input
1000 2000
665759876 597950008 615453266 ...

correct output
498801198 498681904 498504321 ...

user output
498801198 498681904 498504321 ...

Test 18

Group: 5, 6

Verdict:

input
500 2000
683288817 784230412 626685186 ...

correct output
497667621 498434895 495465990 ...

user output
497667621 498434895 495465990 ...

Test 19

Group: 5, 6

Verdict: ACCEPTED

input
1000 2000
666667000 809309500 571572000 ...

correct output
499499500 499249250 498999000 ...

user output
499499500 499249250 498999000 ...

Test 20

Group: 6

Verdict:

input
100000 200000
861772559 734298084 983382252 ...

correct output
499973914 499985299 499985141 ...

user output
(empty)

Test 21

Group: 6

Verdict:

input
30000 200000
691834579 617419813 514778075 ...

correct output
499967533 499976270 499969810 ...

user output
(empty)

Test 22

Group: 6

Verdict:

input
100000 200000
820255000 960780000 741965000 ...

correct output
499995000 499992500 499990000 ...

user output
(empty)