From efa9bd2e2475809426670e0fb3f69b0bc1c6291c Mon Sep 17 00:00:00 2001
From: Aakanksha Garg <2024ucs0077@iitjammu.ac.in>
Date: Mon, 27 Oct 2025 06:16:42 +0000
Subject: [PATCH] added soln for tree distances 1

---
 9_tree_algorithms/Tree_Distances_I.cpp | 78 ++++++++++++++++++++++++++
 1 file changed, 78 insertions(+)
 create mode 100644 9_tree_algorithms/Tree_Distances_I.cpp

diff --git a/9_tree_algorithms/Tree_Distances_I.cpp b/9_tree_algorithms/Tree_Distances_I.cpp
new file mode 100644
index 0000000..55998af
--- /dev/null
+++ b/9_tree_algorithms/Tree_Distances_I.cpp
@@ -0,0 +1,78 @@
+#include <iostream>
+#include <vector>
+#include <algorithm>
+
+using namespace std;
+
+int n;
+vector<vector<int>> adj;
+vector<int> max1_down, max2_down;
+vector<int> up_dist;
+
+void dfs1(int u, int p) {
+    max1_down[u] = 0;
+    max2_down[u] = 0;
+
+    for (int v : adj[u]) {
+        if (v != p) {
+            dfs1(v, u);
+            int dist = max1_down[v] + 1;
+
+            if (dist > max1_down[u]) {
+                max2_down[u] = max1_down[u];
+                max1_down[u] = dist;
+            } else if (dist > max2_down[u]) {
+                max2_down[u] = dist;
+            }
+        }
+    }
+}
+
+void dfs2(int u, int p) {
+    int parent_max_path;
+    
+    if (max1_down[u] + 1 == max1_down[p]) {
+        parent_max_path = max2_down[p];
+    } else {
+        parent_max_path = max1_down[p];
+    }
+    
+    up_dist[u] = max(up_dist[p], parent_max_path) + 1;
+
+    for (int v : adj[u]) {
+        if (v != p) {
+            dfs2(v, u);
+        }
+    }
+}
+
+int main() {
+    ios_base::sync_with_stdio(false);
+    cin.tie(NULL);
+
+    if (!(cin >> n)) return 0;
+
+    adj.resize(n + 1);
+    max1_down.resize(n + 1);
+    max2_down.resize(n + 1);
+    up_dist.resize(n + 1);
+
+    for (int i = 0; i < n - 1; ++i) {
+        int a, b;
+        cin >> a >> b;
+        adj[a].push_back(b);
+        adj[b].push_back(a);
+    }
+
+    dfs1(1, 0);
+
+    up_dist[1] = 0;
+    dfs2(1, 0);
+
+    for (int i = 1; i <= n; ++i) {
+        cout << max(max1_down[i], up_dist[i]) << (i == n ? "" : " ");
+    }
+    cout << "\n";
+
+    return 0;
+}