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Submission #841286

# Submission time Handle Problem Language Result Execution time Memory
841286 2023-09-01T12:50:53 Z I_love_Hoang_Yen Longest Trip (IOI23_longesttrip) C++17
40 / 100
 17 ms 300 KB 
#include "longesttrip.h"
#include <bits/stdc++.h>
using namespace std;

// Subtask 1: D == 3
vector<int> sub1(int n) {
    vector<int> res(n);
    std::iota(res.begin(), res.end(), 0);
    return res;
}

// Subtask 2: D == 2
bool has_edge(int u, int v) {
    return are_connected({u}, {v});
}

vector<int> sub2(int n) {
    vector<int> res {0};
    for (int i = 1; i < n; i++) {
        if (has_edge(0, i)) {
            res.push_back(i);
            break;
        }
    }

    for (int i = 1; i < n; i++) {
        if (i == res[1]) continue;

        if (has_edge(res.back(), i)) {
            res.push_back(i);
        } else {
            res.insert(res.begin(), i);
        }
    }

    return res;
}

// Subtask 3: D == 1, return path with length >= Lmax / 2
vector<int> sub3(int n) {
    // maintain 2 paths
    vector<int> p1 {0}, p2 {1};

    for (int i = 2; i < n; ++i) {
        // consider p1.back(), p2.back(), i
        // -> there's at least 1 edge

        if (has_edge(p1.back(), i)) {
            p1.push_back(i);
        } else if (has_edge(p2.back(), i)) {
            p2.push_back(i);
        } else {
            reverse(p2.begin(), p2.end());
            p1.insert(p1.end(), p2.begin(), p2.end());
            p2 = {i};
        }
    }
    if (p1.size() > p2.size()) return p1;
    return p2;
}

// Subtask 4: D == 1
vector<int> sub4(int n) {
    // Use subtask 3 to get 2 paths {{{
    vector<int> p1 {0}, p2 {1};
    for (int i = 2; i < n; ++i) {
        if (has_edge(p1.back(), i)) {
            p1.push_back(i);
        } else if (has_edge(p2.back(), i)) {
            p2.push_back(i);
        } else {
            reverse(p2.begin(), p2.end());
            p1.insert(p1.end(), p2.begin(), p2.end());
            p2 = {i};
        }
    }
    // }}}
    
    // Make p1 longer path
    if (p1.size() < p2.size()) swap(p1, p2);

    // Impossible to merge 2 paths
    if (!are_connected(p1, p2)) {
        return p1;
    }
    
    // Merge 2 paths:
    // Consider: p1[0], p1.back() and p2[0] -> at least 1 edge
    if (has_edge(p1.back(), p2[0])) {
        p1.insert(p1.end(), p2.begin(), p2.end());
        return p1;
    } else if (has_edge(p1[0], p2[0])) {
        reverse(p2.begin(), p2.end());
        p2.insert(p2.end(), p1.begin(), p1.end());
        return p2;
    } else {
        // p1 is a circle. Find an edge from p2[0] to any vertex in p1
        for (int i = 0; i < n; ++i) {
            if (has_edge(p1[i], p2[0])) {
                reverse(p2.begin(), p2.end());
                p2.insert(p2.end(), p1.begin() + i, p1.end());
                return p2;
            }
        }
    }
}

vector<int> longest_trip(int n, int d) {
    if (d == 3) return sub1(n);
    if (d == 2) return sub2(n);
    return sub3(n);
}

Compilation message

longesttrip.cpp: In function 'std::vector<int> sub4(int)':
longesttrip.cpp:65:22: warning: control reaches end of non-void function [-Wreturn-type]
   65 |     vector<int> p1 {0}, p2 {1};
      |                      ^

Subtask #0
0.0 / 0.0

# Verdict Execution time Memory Grader output
1 Incorrect 1 ms 208 KB Incorrect
2 Halted 0 ms 0 KB -

Subtask #1
5.0 / 5.0

# Verdict Execution time Memory Grader output
1 Correct 2 ms 208 KB Output is correct
2 Correct 2 ms 208 KB Output is correct
3 Correct 1 ms 208 KB Output is correct
4 Correct 1 ms 220 KB Output is correct
5 Correct 0 ms 208 KB Output is correct

Subtask #2
10.0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 10 ms 208 KB Output is correct
2 Correct 7 ms 208 KB Output is correct
3 Correct 6 ms 208 KB Output is correct
4 Correct 11 ms 208 KB Output is correct
5 Correct 7 ms 296 KB Output is correct
6 Correct 8 ms 228 KB Output is correct
7 Correct 8 ms 208 KB Output is correct
8 Correct 8 ms 208 KB Output is correct
9 Correct 10 ms 208 KB Output is correct
10 Correct 11 ms 208 KB Output is correct
11 Correct 8 ms 208 KB Output is correct
12 Correct 10 ms 208 KB Output is correct
13 Correct 9 ms 208 KB Output is correct

Subtask #3
25.0 / 25.0

# Verdict Execution time Memory Grader output
1 Correct 7 ms 208 KB Output is correct
2 Correct 8 ms 208 KB Output is correct
3 Correct 8 ms 208 KB Output is correct
4 Correct 10 ms 208 KB Output is correct
5 Correct 9 ms 208 KB Output is correct
6 Correct 6 ms 208 KB Output is correct
7 Correct 9 ms 208 KB Output is correct
8 Correct 8 ms 208 KB Output is correct
9 Correct 9 ms 208 KB Output is correct
10 Correct 9 ms 208 KB Output is correct
11 Correct 7 ms 208 KB Output is correct
12 Correct 6 ms 208 KB Output is correct
13 Correct 10 ms 208 KB Output is correct
14 Correct 7 ms 208 KB Output is correct
15 Correct 5 ms 208 KB Output is correct
16 Correct 11 ms 208 KB Output is correct
17 Correct 8 ms 208 KB Output is correct
18 Correct 7 ms 208 KB Output is correct
19 Correct 6 ms 208 KB Output is correct
20 Correct 6 ms 208 KB Output is correct
21 Correct 8 ms 208 KB Output is correct
22 Correct 8 ms 208 KB Output is correct
23 Correct 7 ms 208 KB Output is correct
24 Correct 5 ms 208 KB Output is correct
25 Correct 10 ms 208 KB Output is correct
26 Correct 10 ms 208 KB Output is correct
27 Correct 9 ms 208 KB Output is correct
28 Correct 5 ms 256 KB Output is correct
29 Correct 7 ms 208 KB Output is correct
30 Correct 12 ms 208 KB Output is correct
31 Correct 10 ms 208 KB Output is correct
32 Correct 13 ms 208 KB Output is correct
33 Correct 11 ms 208 KB Output is correct
34 Correct 7 ms 208 KB Output is correct
35 Correct 13 ms 208 KB Output is correct
36 Correct 7 ms 208 KB Output is correct
37 Correct 7 ms 208 KB Output is correct
38 Correct 11 ms 208 KB Output is correct
39 Correct 10 ms 300 KB Output is correct
40 Correct 17 ms 228 KB Output is correct
41 Correct 10 ms 300 KB Output is correct
42 Correct 13 ms 208 KB Output is correct
43 Correct 6 ms 208 KB Output is correct
44 Correct 7 ms 300 KB Output is correct
45 Correct 8 ms 208 KB Output is correct
46 Correct 11 ms 208 KB Output is correct
47 Correct 11 ms 208 KB Output is correct
48 Correct 10 ms 208 KB Output is correct
49 Correct 10 ms 208 KB Output is correct
50 Correct 9 ms 208 KB Output is correct
51 Correct 13 ms 208 KB Output is correct
52 Correct 13 ms 208 KB Output is correct
53 Correct 11 ms 208 KB Output is correct
54 Correct 6 ms 208 KB Output is correct
55 Correct 13 ms 228 KB Output is correct
56 Correct 8 ms 208 KB Output is correct
57 Correct 9 ms 208 KB Output is correct
58 Correct 10 ms 300 KB Output is correct
59 Correct 11 ms 240 KB Output is correct
60 Correct 11 ms 208 KB Output is correct
61 Correct 12 ms 208 KB Output is correct
62 Correct 14 ms 208 KB Output is correct
63 Correct 8 ms 208 KB Output is correct
64 Correct 8 ms 208 KB Output is correct

Subtask #4
0.0 / 60.0

# Verdict Execution time Memory Grader output
1 Incorrect 1 ms 208 KB Incorrect
2 Halted 0 ms 0 KB -