<p>There is an undirected connected tree with <code>n</code> nodes labeled from <code>0</code> to <code>n - 1</code> and <code>n - 1</code> edges.</p>

<p>You are given the integer <code>n</code> and the array <code>edges</code> where <code>edges[i] = [a<sub>i</sub>, b<sub>i</sub>]</code> indicates that there is an edge between nodes <code>a<sub>i</sub></code> and <code>b<sub>i</sub></code> in the tree.</p>

<p>Return an array <code>answer</code> of length <code>n</code> where <code>answer[i]</code> is the sum of the distances between the <code>i<sup>th</sup></code> node in the tree and all other nodes.</p>

<p>&nbsp;</p>
<p><strong class="example">Example 1:</strong></p>
<img alt="" src="https://assets.leetcode.com/uploads/2021/07/23/lc-sumdist1.jpg" style="width: 304px; height: 224px;" />
<pre>
<strong>Input:</strong> n = 6, edges = [[0,1],[0,2],[2,3],[2,4],[2,5]]
<strong>Output:</strong> [8,12,6,10,10,10]
<strong>Explanation:</strong> The tree is shown above.
We can see that dist(0,1) + dist(0,2) + dist(0,3) + dist(0,4) + dist(0,5)
equals 1 + 1 + 2 + 2 + 2 = 8.
Hence, answer[0] = 8, and so on.
</pre>

<p><strong class="example">Example 2:</strong></p>
<img alt="" src="https://assets.leetcode.com/uploads/2021/07/23/lc-sumdist2.jpg" style="width: 64px; height: 65px;" />
<pre>
<strong>Input:</strong> n = 1, edges = []
<strong>Output:</strong> [0]
</pre>

<p><strong class="example">Example 3:</strong></p>
<img alt="" src="https://assets.leetcode.com/uploads/2021/07/23/lc-sumdist3.jpg" style="width: 144px; height: 145px;" />
<pre>
<strong>Input:</strong> n = 2, edges = [[1,0]]
<strong>Output:</strong> [1,1]
</pre>

<p>&nbsp;</p>
<p><strong>Constraints:</strong></p>

<ul>
	<li><code>1 &lt;= n &lt;= 3 * 10<sup>4</sup></code></li>
	<li><code>edges.length == n - 1</code></li>
	<li><code>edges[i].length == 2</code></li>
	<li><code>0 &lt;= a<sub>i</sub>, b<sub>i</sub> &lt; n</code></li>
	<li><code>a<sub>i</sub> != b<sub>i</sub></code></li>
	<li>The given input represents a valid tree.</li>
</ul>

class Solution {
public:
unordered_map<int, vector<int>> map;
vector<bool> visited;
vector<int> zeroAns;
vector<int> child;
vector<int> ans;
    vector<int> sumOfDistancesInTree(int n, vector<vector<int>>& edges) {

        for (int i = 0; i < edges.size(); i++) {
            map[edges[i][0]].push_back(edges[i][1]);
            map[edges[i][1]].push_back(edges[i][0]);
        }

        visited.resize(n, false);
        zeroAns.resize(n, 0);
        child.resize(n, 1);

        dfs(0, 0);

        ans.resize(n, 0);

        for (int i = 0; i < n; i++)
            ans[0] += zeroAns[i];

        visited.assign(n, false);
        
        ansDfs(0, n);
        return ans;
    }

    int dfs(int node, int d) {
        visited[node] = true;
        zeroAns[node] = d;

        int temp = 1;
        for (int i = 0; i < map[node].size(); i++)
            if (!visited[map[node][i]]) 
                temp += dfs(map[node][i], d + 1);

        child[node] = temp;

        return temp;
    }

    void ansDfs(int node, int n) {
        visited[node] = true;

        for (int i = 0; i < map[node].size(); i++)
            if (!visited[map[node][i]]) {
                int temp = map[node][i];
                ans[temp] = ans[node] + (-1 * child[temp]) + (n - child[temp]);
                ansDfs(temp, n);
            }
    }
};
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