CSES - Datatähti 2024 alku

Submission details
Task:	Käännöt
Sender:	Username*
Submission time:	2023-11-11 13:45:18 +0200
Language:	C++ (C++20)
Status:	READY
Result:	100

Feedback
group	verdict	score
#1	ACCEPTED	13
#2	ACCEPTED	19
#3	ACCEPTED	33
#4	ACCEPTED	35

Test results
test	verdict	time	group
#1	ACCEPTED	0.00 s	1	details
#2	ACCEPTED	0.00 s	1	details
#3	ACCEPTED	0.00 s	1	details
#4	ACCEPTED	0.00 s	1	details
#5	ACCEPTED	0.00 s	1	details
#6	ACCEPTED	0.00 s	2	details
#7	ACCEPTED	0.00 s	2	details
#8	ACCEPTED	0.00 s	2	details
#9	ACCEPTED	0.00 s	2	details
#10	ACCEPTED	0.00 s	2	details
#11	ACCEPTED	0.01 s	2	details
#12	ACCEPTED	0.01 s	2	details
#13	ACCEPTED	0.01 s	2	details
#14	ACCEPTED	0.01 s	2	details
#15	ACCEPTED	0.00 s	2	details
#16	ACCEPTED	0.01 s	2	details
#17	ACCEPTED	0.00 s	3	details
#18	ACCEPTED	0.00 s	3	details
#19	ACCEPTED	0.01 s	3	details
#20	ACCEPTED	0.01 s	3	details
#21	ACCEPTED	0.01 s	3	details
#22	ACCEPTED	0.01 s	3	details
#23	ACCEPTED	0.01 s	3	details
#24	ACCEPTED	0.00 s	3	details
#25	ACCEPTED	0.01 s	3	details
#26	ACCEPTED	0.00 s	4	details
#27	ACCEPTED	0.00 s	4	details
#28	ACCEPTED	0.01 s	4	details
#29	ACCEPTED	0.01 s	4	details
#30	ACCEPTED	0.01 s	4	details
#31	ACCEPTED	0.01 s	4	details
#32	ACCEPTED	0.00 s	4	details
#33	ACCEPTED	0.01 s	4	details
#34	ACCEPTED	0.01 s	4	details

Compiler report

input/code.cpp: In function 'int inversions(std::vector<int>)':
input/code.cpp:11:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   11 |     for (int i = 0; i < vec.size(); ++i) {
      |                     ~~^~~~~~~~~~~~
input/code.cpp:12:29: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   12 |         for (int j = i+1; j < vec.size(); ++j) {
      |                           ~~^~~~~~~~~~~~
input/code.cpp: In function 'bool parity(std::vector<int>)':
input/code.cpp:23:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   23 |     for (int i = 0; i < vec.size(); ++i) {
      |                     ~~^~~~~~~~~~~~

Code

#include <vector>
#include <algorithm>
#include <iostream>
#include <queue>
#include <map>

using namespace std;

int inversions(vector<int> vec) { //check inversions for k=4
    int inversions = 0;
    for (int i = 0; i < vec.size(); ++i) {
        for (int j = i+1; j < vec.size(); ++j) {
            if (vec[j] < vec[i]) {
                ++inversions;
            }
        }
    }
    //cout << "INV: " << inversions << endl;
    return inversions;
}

bool parity(vector<int> vec) {
    for (int i = 0; i < vec.size(); ++i) {
        if ((vec[i] & 1) != ((i + 1) & 1)) { // if a value and its index have mismatching parity, applicable for k=3, k=5
            return false;
        }
    }
    return true;
}

vector<int> bfs(vector<int> vec, int k) {
    vector<int> steps = {};

    int n = vec.size();

    vector<int> sorted = vec;
    sort(sorted.begin(), sorted.end());

    map<vector<int>, int> dist; // map of lists and their distances to start
    map<vector<int>, int> parent; // map of lists and the previous operation used to reach it

    queue<vector<int>> q; // bfs queue

    dist[vec] = 0; // the intial list is distance 0
    q.push(vec); // start with the initial list

    while (!q.empty()) { // checks all possibilities until it finds a solution
        vector<int> cur = q.front(); // checking the first value of queue
        q.pop();

        if (cur == sorted) { //end if sorted was found
            break;
        }

        for (int i = 0; i <= n - k; i++) { // for all possible reversals
            vector<int> next = cur;
            reverse(next.begin() + i, next.begin() + i + k);
            if (!dist.count(next)) { // if not already found
                dist[next] = dist[cur] + 1;
                parent[next] = i + 1;
                q.push(next); // add substates to queue to check
            }
        }
    }

    if (dist.count(sorted)) {
        for (vector<int> v = sorted; v != vec; v = v) {
            steps.push_back(parent[v]);
            reverse(v.begin() + parent[v] - 1, v.begin() + parent[v] - 1 + k);
        }
        reverse(steps.begin(), steps.end()); //reverse steps because they were traced back
    }

    return steps;
}

vector<int> solve(int n, int k, vector<int> vec) {
    vector<int> steps = {};

    int invs = inversions(vec);

    if (k == 3 || k == 5) {
        if (!parity(vec)) {
            //cout << "\nParity : unsolvable\n";
            return steps;
        }
    }

    if (k == 4) {
        if (invs & 1) { // number of inversions is odd : unsolvable with k=4
            //cout << "\nInversion parity with k=4 : unsolvable\n";
            return steps;
        }
        if (n <= 6) {
            //cout << "\nDoing bfs, short list w/ k=4\n";
            return bfs(vec, k);
        }
    }

    vector<int> moveset;

    bool run = true;
    int ceil = n-1; // ceiling based on sorted values
    int cur = n; // current value to sort
    int curi = -1; // current index of the value to sort
    while (run) {
        for (int i = ceil; i >= 0; --i) { // find largest unsorted value
            if (vec[i] == cur) {
                if (vec[i] == i + 1) {
                    --ceil;
                    --cur;
                    //cout << "\nSkip: " << cur;
                    if (ceil < k + 2 && k>3) {
                        //cout << "\nCEIL: " << ceil;
                        run = false;
                        break;
                    }
                    continue;
                }
                curi = i;
                //cout << "\nCur: " << cur << " & Cur i: " << curi;
                break; // found
            }
        }

        if (run == false) {
            break;
        }

        // sort the found value to its spot
        int targeti = cur - k; // 

        //cout << "\nTarget: " << targeti;

        while (curi != targeti) {
            int dist = targeti - curi;
            bool right = dist > 0;
            dist = abs(dist);

            //cout << "\nDistance: " << dist;
            //cout << "\nk-1: " << k-1;

            if (k - 1 <= dist) {
                steps.push_back(curi+1);
                reverse(vec.begin() + curi, vec.begin() + curi + k);
                curi += (k - 1);
                //cout << "\ncuri now " << curi;
                /*cout << "\n";
                for (int i : vec) {
                    cout << " " << i;
                }*/
            }
            else { // closer than k to target
                if (curi == 0) { // at the leftmost side, value has to be moved out first
                    steps.push_back(curi+1);
                    reverse(vec.begin() + curi, vec.begin() + curi + k);
                    curi += (k - 1);
                    /*cout << "\n";
                    for (int i : vec) {
                        cout << " " << i;
                    }*/
                    continue;
                }
                //cout << "\nclose to tgt";
                if (k == 4) {
                    if (right) {
                        for (int i = 0; i < dist; ++i) {
                            steps.push_back(curi);
                            reverse(vec.begin() + curi - 1, vec.begin() + curi + k-1);
                            ++curi;
                        }
                        //cout << "\ngoing tgt";
                    }
                    else { // edge case where value has ended up past the target
                        for (int i = 0; i < dist; ++i) {
                            steps.push_back(curi-1);
                            reverse(vec.begin() + curi - 2, vec.begin() + curi + k - 2);
                            --curi;
                        }
                        //cout << "\npast tgt";
                    }
                }
                else if (k == 5) {
                    if (right) {
                        steps.push_back(curi);
                        reverse(vec.begin() + curi - 1, vec.begin() + curi + k - 1);
                        curi += 2;
                        //cout << "\ngoing tgt";
                    }
                    else { // edge case where value has ended up past the target
                        steps.push_back(curi - 2);
                        reverse(vec.begin() + curi - 3, vec.begin() + curi + k - 3);
                        curi -= 2;
                        //cout << "\npast tgt";
                    }
                }
                break;
            }
        }

        //cout << "\nREACHED TARGET";

        /*cout << "\n";
        for (int i : vec) {
            cout << " " << i;
        }*/
        steps.push_back(curi + 1);
        reverse(vec.begin() + curi, vec.begin() + curi + k);

        //cout << "\nDONE";

        /*cout << "\n";
        for (int i : vec) {
            cout << " " << i;
        }*/


        if (is_sorted(vec.begin(), vec.end())) {
            break;
        }
    }

    /*cout << "\nFINAL LIST :: \n";
    cout << "\n";
    for (int i : vec) {
        cout << " " << i;
    }*/

    if (!is_sorted(vec.begin(), vec.end())) {
        if (k > 3) { // find solution to unsorted part using bfs
            vector<int> subvec(vec.begin(), vec.begin() + k + 2);
            vector<int> substeps = bfs(subvec, k);
            if (substeps.size() > 0) {
                steps.insert(steps.end(), substeps.begin(), substeps.end());
            }
            else {
                steps = {};
            }
        }
    }
    //cout << "\n";
    return steps;
}

int main() {
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);


    // take inputs
    int n, k;
    cin >> n;
    cin >> k;

    vector<int> vec(n);

    for (int i = 0; i < n; i++) {
        cin >> vec[i];
    }
    // end of inputs

    if (is_sorted(vec.begin(), vec.end())) { //already sorted, return YES 0
        cout << "YES\n" << 0;
        return 0;
    }

    vector<int> steps = solve(n, k, vec);

    if (steps.size() > 0) {
        cout << "YES" << "\n" << steps.size() << "\n";
        for (int step : steps) cout << step << " ";
        cout << "\n";
    }
    else {
        cout << "NO" << "\n";
    }

    return 0;
}

Test details

Test 1

Group: 1

Verdict: ACCEPTED

input
`5 2 1 2 3 4 5` view save

correct output
`YES 0` view save

user output
`YES 0` view save

Test 2

Group: 1

Verdict: ACCEPTED

input
`5 2 2 1 3 4 5` view save

correct output
`YES 1 1` view save

user output
`YES 1 1` view save

Test 3

Group: 1

Verdict: ACCEPTED

input
`20 2 6 20 18 2 16 13 19 17 8 14 11 ...` view save

correct output
`YES 366 2 3 4 5 6 7 8 9 10 11 12 13 14...` view save

user output
`YES 132 2 3 4 5 6 7 8 9 10 11 12 13 14...` Truncated

Test 4

Group: 1

Verdict: ACCEPTED

input
`100 2 100 92 62 88 12 7 43 31 19 72 ...` view save

correct output
`YES 2876 1 2 3 4 5 6 7 8 9 10 11 12 13 ...` view save

user output
`YES 2438 1 2 3 4 5 6 7 8 9 10 11 12 13 ...` Truncated

Test 5

Group: 1

Verdict: ACCEPTED

input
`100 2 100 99 98 97 96 95 94 93 92 91...` view save

correct output
`YES 5248 1 2 3 4 5 6 7 8 9 10 11 12 13 ...` view save

user output
`YES 4950 1 2 3 4 5 6 7 8 9 10 11 12 13 ...` Truncated

Test 6

Group: 2

Verdict: ACCEPTED

input
`5 3 1 2 3 4 5` view save

correct output
`YES 0` view save

user output
`YES 0` view save

Test 7

Group: 2

Verdict: ACCEPTED

input
`5 3 3 5 4 1 2` view save

correct output
`NO` view save

user output
`NO` view save

Test 8

Group: 2

Verdict: ACCEPTED

input
`5 3 5 2 1 4 3` view save

correct output
`YES 8 1 2 1 3 1 2 3 1` view save

user output
`YES 2 1 3` view save

Test 9

Group: 2

Verdict: ACCEPTED

input
`20 3 19 14 1 18 3 4 11 20 13 6 17 8...` view save

correct output
`YES 52 8 10 12 14 16 18 1 3 5 7 9 11 ...` view save

user output
`YES 42 8 10 12 14 16 18 1 3 5 7 9 11 ...` Truncated

Test 10

Group: 2

Verdict: ACCEPTED

input
`20 3 9 6 13 18 5 10 3 2 7 20 1 4 19...` view save

correct output
`YES 50 10 12 14 16 18 13 15 17 4 6 8 ...` view save

user output
`YES 34 10 12 14 16 18 13 15 17 4 6 8 ...` view save

Test 11

Group: 2

Verdict: ACCEPTED

input
`500 3 53 52 21 76 25 142 5 4 83 176 ...` view save

correct output
`YES 15194 334 336 338 340 342 344 346 34...` view save

user output
`YES 15174 334 336 338 340 342 344 346 34...` Truncated

Test 12

Group: 2

Verdict: ACCEPTED

input
`500 3 51 44 147 172 1 28 27 82 233 1...` view save

correct output
`YES 15565 366 368 370 372 374 376 378 38...` view save

user output
`YES 15543 366 368 370 372 374 376 378 38...` Truncated

Test 13

Group: 2

Verdict: ACCEPTED

input
`500 3 75 46 179 62 221 14 67 154 89 ...` view save

correct output
`YES 15920 454 456 458 460 462 464 466 46...` view save

user output
`YES 15902 454 456 458 460 462 464 466 46...` Truncated

Test 14

Group: 2

Verdict: ACCEPTED

input
`500 3 161 54 285 12 71 142 111 94 97...` view save

correct output
`YES 15931 408 410 412 414 416 418 420 42...` view save

user output
`YES 15907 408 410 412 414 416 418 420 42...` Truncated

Test 15

Group: 2

Verdict: ACCEPTED

input
`500 3 122 260 455 113 315 276 433 43...` view save

correct output
`NO` view save

user output
`NO` view save

Test 16

Group: 2

Verdict: ACCEPTED

input
`500 3 499 500 497 498 495 496 493 49...` view save

correct output
`YES 62264 2 4 6 8 10 12 14 16 18 20 22 2...` view save

user output
`YES 62250 2 4 6 8 10 12 14 16 18 20 22 2...` Truncated

Test 17

Group: 3

Verdict: ACCEPTED

input
`5 4 1 2 3 4 5` view save

correct output
`YES 0` view save

user output
`YES 0` view save

Test 18

Group: 3

Verdict: ACCEPTED

input
`5 4 5 1 2 3 4` view save

correct output
`YES 4 1 2 1 2` view save

user output
`YES 4 1 2 1 2` view save

Test 19

Group: 3

Verdict: ACCEPTED

input
`500 4 58 14 107 124 4 113 24 290 56 ...` view save

correct output
`YES 15698 389 392 395 398 401 404 407 41...` view save

user output
`YES 14501 389 392 395 398 401 404 407 41...` Truncated

Test 20

Group: 3

Verdict: ACCEPTED

input
`500 4 113 187 278 242 23 67 48 298 3...` view save

correct output
`YES 15004 480 481 480 482 485 488 491 49...` view save

user output
`YES 13637 484 487 490 493 495 497 492 49...` Truncated

Test 21

Group: 3

Verdict: ACCEPTED

input
`500 4 5 233 199 35 213 354 11 134 30...` view save

correct output
`YES 16770 458 461 464 467 470 473 476 47...` view save

user output
`YES 15413 458 461 464 467 470 473 476 47...` Truncated

Test 22

Group: 3

Verdict: ACCEPTED

input
`500 4 169 47 21 137 57 138 360 147 4...` view save

correct output
`YES 15889 497 371 372 371 373 376 379 38...` view save

user output
`YES 14701 497 375 378 381 384 387 390 39...` Truncated

Test 23

Group: 3

Verdict: ACCEPTED

input
`500 4 493 409 291 313 156 443 496 40...` view save

correct output
`YES 22886 480 481 480 482 485 488 491 49...` view save

user output
`YES 21508 484 487 490 493 495 497 137 14...` Truncated

Test 24

Group: 3

Verdict: ACCEPTED

input
`500 4 137 99 100 226 326 298 140 340...` view save

correct output
`NO` view save

user output
`NO` view save

Test 25

Group: 3

Verdict: ACCEPTED

input
`500 4 500 499 498 497 496 495 494 49...` view save

correct output
`YES 41458 1 2 1 2 5 8 11 14 17 20 23 26 ...` view save

user output
`YES 41789 1 4 7 10 13 16 19 22 25 28 31 ...` Truncated

Test 26

Group: 4

Verdict: ACCEPTED

input
`5 5 1 2 3 4 5` view save

correct output
`YES 0` view save

user output
`YES 0` view save

Test 27

Group: 4

Verdict: ACCEPTED

input
`5 5 5 4 3 2 1` view save

correct output
`YES 1 1` view save

user output
`YES 1 1` view save

Test 28

Group: 4

Verdict: ACCEPTED

input
`500 5 145 26 285 154 147 314 141 40 ...` view save

correct output
`YES 13786 216 220 224 228 232 236 240 24...` view save

user output
`YES 13082 216 220 224 228 232 236 240 24...` Truncated

Test 29

Group: 4

Verdict: ACCEPTED

input
`500 5 137 22 399 292 249 6 51 224 42...` view save

correct output
`YES 13465 456 460 464 468 472 476 480 48...` view save

user output
`YES 12735 456 460 464 468 472 476 480 48...` Truncated

Test 30

Group: 4

Verdict: ACCEPTED

input
`500 5 153 52 85 100 329 60 433 468 4...` view save

correct output
`YES 13642 377 378 377 380 384 388 392 39...` view save

user output
`YES 12920 382 386 390 394 398 402 406 41...` Truncated

Test 31

Group: 4

Verdict: ACCEPTED

input
`500 5 267 326 95 108 189 32 291 366 ...` view save

correct output
`YES 14639 213 214 213 216 220 224 228 23...` view save

user output
`YES 13889 218 222 226 230 234 238 242 24...` Truncated

Test 32

Group: 4

Verdict: ACCEPTED

input
`500 5 15 450 272 80 321 101 247 438 ...` view save

correct output
`NO` view save

user output
`NO` view save

Test 33

Group: 4

Verdict: ACCEPTED

input
`499 5 497 498 499 496 495 494 493 49...` view save

correct output
`YES 30886 3 7 11 15 19 23 27 31 35 39 43...` view save

user output
`YES 30876 3 7 11 15 19 23 27 31 35 39 43...` Truncated

Test 34

Group: 4

Verdict: ACCEPTED

input
`500 5 499 500 497 498 495 496 493 49...` view save

correct output
`YES 30919 1 4 8 12 16 20 24 28 32 36 40 ...` view save

user output
`YES 31247 2 6 10 14 18 22 26 30 34 38 42...` Truncated

Datatähti 2024 alku

Käännöt

Compiler report

Code

Test details

Test 1

Test 2

Test 3

Test 4

Test 5

Test 6

Test 7

Test 8

Test 9

Test 10

Test 11

Test 12

Test 13

Test 14

Test 15

Test 16

Test 17

Test 18

Test 19

Test 20

Test 21

Test 22

Test 23

Test 24

Test 25

Test 26

Test 27

Test 28

Test 29

Test 30

Test 31

Test 32

Test 33

Test 34

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