Create tree_height.py

2. Data Structures/2_tree_height.py/tree_height.py

@@ -0,0 +1,33 @@
+# python3
+
+import sys
+import threading
+import collections
+
+def compute_height(n, parents):
+    # Replace this code with a faster implementation
+    max_height = -1
+    tree = collections.defaultdict(list)
+    q = collections.deque([-1])
+    for i, node in enumerate(parents):
+        tree[node].append(i)
+    while q:
+        max_height += 1
+        l = len(q)
+        for _ in range(l):
+            node = q.popleft()
+            q.extend(tree[node])
+    return max_height
+
+def main():
+    n = int(input())
+    parents = list(map(int, input().split()))
+    print(compute_height(n, parents))
+
+
+# In Python, the default limit on recursion depth is rather low,
+# so raise it here for this problem. Note that to take advantage
+# of bigger stack, we have to launch the computation in a new thread.
+sys.setrecursionlimit(10**7)  # max depth of recursion
+threading.stack_size(2**27)   # new thread will get stack of such size
+threading.Thread(target=main).start()