我自己能想到的测试数据基本都试过了，没问题，但提交全是WA

#include <iostream>
#include <map>

using namespace std;

int main()
{
    int n = 0;
    cin >> n;

    int maxNum = 0;
    map<int, int> mp;
    mp[1] = 1;
    for (int i = 1; i <= n; ++i)
    {
        int l = 0;
        int r = 0;
        cin >> l >> r;

        int idx = mp[i];
        if (idx != 0)
        {
            if (l != 0)
            {
                maxNum = 2 * idx;
                mp[l] = idx * 2;
            }

            if (r != 0)
            {
                maxNum = 2 * idx + 1;
                mp[r] = idx * 2 + 1;
            }
        }
    }
    int h = 0;
    do
    {
        maxNum /= 2;
        ++h;
    } while (maxNum != 0);

    cout << h << endl;
}