HDU

HDU5444 Elven Postman

題目連結

  • 題意：給定一顆二元樹，給定多筆詢問，每筆詢問需要將起點到 $x$ 的路徑方向。
  • 題解：建立好二元樹後，依據數字大小判斷要往哪個方向拜訪。
    1
    2
    3
    4
    5
    6
    7
    8
    9
    10
    11
    12
    13
    14
    15
    16
    17
    18
    19
    20
    21
    22
    23
    24
    25
    26
    27
    28
    29
    30
    31
    32
    33
    34
    35
    36
    37
    38
    39
    40
    41
    42
    43
    44
    45
    46
    47
    48
    49
    50
    51
    52
    53
    54
    55
    56
    57
    58
    59
    60
    61
    62
    63
    64
    65
    66
    67
    68
    69
    70
    71
    72
    73
    74
    75
    76
    77
    78
    79
    80
    81
    82
    83
    84
    85
    86
    87
    88
    89
    90
    91
    #pragma GCC optimize("O2")
    #include <bits/stdc++.h>
    using namespace std;
    using LL = long long;
    using ULL = unsigned long long;
    using PII = pair<int, int>;
    using PLL = pair<LL, LL>;
    using VI = vector<int>;
    using VVI = vector<vector<int>>;
    const int INF = 1e9;
    const int MXN = 0;
    const int MXV = 0;
    const double EPS = 1e-9;
    const int MOD = 1e9 + 7;
    #define MP make_pair
    #define PB push_back
    #define F first
    #define S second
    #define FOR(i, L, R) for (int i = L; i < (int)R; ++i)
    #define FORD(i, L, R) for (int i = L; i > (int)R; --i)
    #define IOS                                                                    \
        cin.tie(nullptr);                                                          \
        cout.tie(nullptr);                                                         \
        ios_base::sync_with_stdio(false);
    struct Node
    {
        int val;
        Node *Lc, *Rc;
        Node() : Lc(nullptr), Rc(nullptr) {}
    };

    Node *insert(Node *node, int val)
    {
        if (node == nullptr)
        {
            node = new Node();
            node->val = val;
        }
        else if (val < node->val)
        {
            node->Lc = insert(node->Lc, val);
        }
        else
        {
            node->Rc = insert(node->Rc, val);
        }
        return node;
    }

    void dfs(Node *node, int val)
    {
        if (node == nullptr || node->val == val)
        {
            return;
        }
        if (val < node->val)
        {
            cout << 'E';
            dfs(node->Lc, val);
        }
        else
        {
            cout << 'W';
            dfs(node->Rc, val);
        }
    }

    int main()
    {
        IOS;
        int t;
        cin >> t;
        while (t--)
        {
            int n, q, x;
            cin >> n;
            Node *root = nullptr;
            FOR(i, 0, n)
            {
                cin >> x;
                root = insert(root, x);
            }
            cin >> q;
            FOR(i, 0, q)
            {
                cin >> x;
                dfs(root, x);
                cout << '\n';
            }
        }
    }

如果你覺得這篇文章很棒，請你不吝點讚 (ﾟ∀ﾟ)

Recommended Posts