Solution.cpp

class Solution {
public:
    bool validateBinaryTreeNodes(int n, vector<int>& leftChild, vector<int>& rightChild) {
        int p[n];
        iota(p, p + n, 0);
        bool vis[n];
        memset(vis, 0, sizeof(vis));
        function<int(int)> find = [&](int x) {
            return p[x] == x ? x : p[x] = find(p[x]);
        };
        for (int i = 0, m = n; i < m; ++i) {
            for (int j : {leftChild[i], rightChild[i]}) {
                if (j != -1) {
                    if (vis[j] || find(i) == find(j)) {
                        return false;
                    }
                    p[find(i)] = find(j);
                    vis[j] = true;
                    --n;
                }
            }
        }
        return n == 1;
    }
};