题解 | #输出二叉树的右视图#

class Solution {
  public:
    int result[10010], cnt = 1, len = 0, ind = 1;
    void build(int i, vector<int>pre, int l, int r, vector<int>& hx) {
        if (l > r)return;
        result[i] = pre[len];
        int k = l - 1;
        while (pre[len] != hx[++k]);
        len++;
        build(i + i, pre, l, k - 1, hx), build(i + i + 1, pre, k + 1, r, hx);
    }
    vector<int> solve(vector<int>& xianxu, vector<int>& zhongxu) {
        memset(result, 0, sizeof(result));
        build(1, xianxu, 0, zhongxu.size() - 1, zhongxu);
        vector<int>ans;
        while (1) {
            int val = 0;
            for (int i = 0; i < cnt; i++) {
                if (result[ind])val = result[ind];
                ind++;
            }
            cnt *= 2;
            if (!val)break;
            ans.push_back(val);
        }
        return ans;
    }
};