From a4c311fdaa1a587255f01f584c42ca9bea5e1202 Mon Sep 17 00:00:00 2001
From: ISHAN RAJ SINGH <srajishan21@gmail.com>
Date: Wed, 7 Jan 2026 21:13:19 +0530
Subject: [PATCH] Add DFS solution for Codeforces problem 813

Implemented a DFS-based solution to find the maximum distance Bob can delay based on optimal moves.
---
 .../Day-11/sol/ishanrajsingh/Solution2.py     | 37 +++++++++++++++++++
 1 file changed, 37 insertions(+)
 create mode 100644 Problems/Graph/Day-11/sol/ishanrajsingh/Solution2.py

diff --git a/Problems/Graph/Day-11/sol/ishanrajsingh/Solution2.py b/Problems/Graph/Day-11/sol/ishanrajsingh/Solution2.py
new file mode 100644
index 00000000..64cdcf9f
--- /dev/null
+++ b/Problems/Graph/Day-11/sol/ishanrajsingh/Solution2.py
@@ -0,0 +1,37 @@
+# Submission: https://codeforces.com/contest/813/submission/356818920
+# Approach: find the farthest node bob can delay to by dfs the distances and simulate optimal moves
+# Runtime: O(n)
+import sys
+sys.setrecursionlimit(500000)
+input=sys.stdin.readline
+
+n,x=map(int,input().split())
+x-=1
+g=[[] for _ in range(n)]
+for _ in range(n-1):
+    u,v=map(int,input().split())
+    u-=1; v-=1
+    g[u].append(v)
+    g[v].append(u)
+
+distA=[-1]*n
+distB=[-1]*n
+
+def dfs(start,dist):
+    stack=[start]
+    dist[start]=0
+    while stack:
+        u=stack.pop()
+        for v in g[u]:
+            if dist[v]==-1:
+                dist[v]=dist[u]+1
+                stack.append(v)
+
+dfs(0,distA)
+dfs(x,distB)
+
+ans=0
+for i in range(n):
+    if distB[i]>distA[i]:
+        ans=max(ans,distA[i]+distB[i])
+print(ans+1)