HDU

HDU5524 Subtrees

題目連結

  • 題意：給定一顆 $N$ 個點的完全二元樹，問有幾個不同 size 的子樹。
  • 題解：對於一顆滿二元樹，答案會是這棵樹的高度；對於一顆非滿二元樹，每往下一層，答案就 +1
  • 參考：https://blog.csdn.net/kyoma/article/details/52072829
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    #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);
    LL n;
    LL maxn, ans;

    void sol(LL x)
    {
        LL L = x, R = x, dep = 0;
        for (L = x; 2 * L <= n; ++dep)
        {
            L *= 2;
        }
        for (; 2 * R + 1 <= n;)
        {
            R = 2 * R + 1;
        }
        if (L <= R)
        {
            maxn = max(maxn, dep);
        }
        else
        {
            ++ans;
            sol(2 * x);
            sol(2 * x + 1);
        }
    }

    int main()
    {
        IOS;
        while (cin >> n)
        {
            maxn = ans = 0;
            sol(1);
            cout << maxn + ans + 1 << '\n';
        }
    }

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