added journey-to-the-moon

Author: eloyekunle

hackerrank/graphs/journey-to-the-moon.py

@@ -0,0 +1,57 @@
+import math
+import os
+import random
+import re
+import sys
+from collections import Counter
+
+def dfs(g, u, discovered, c):
+ for v in g[u]:
+ if v not in discovered:
+ discovered[v] = c
+ dfs(g, v, discovered, c)
+
+def journeyToMoon(n, astronaut):
+ g = {}
+ for i in range(n):
+ g[i] = set()
+
+ for a, b in astronaut:
+ g[a].add(b)
+ g[b].add(a)
+
+ forest = {}
+ component = 0
+ for v in range(n):
+ if v not in forest:
+ forest[v] = component
+ dfs(g, v, forest, component)
+ component += 1
+
+ vs = Counter(forest.values()).values()
+
+ c_sum = 0
+ result = 0
+ for s in vs:
+ result += c_sum * s
+ c_sum += s
+
+ return result
+
+if __name__ == '__main__':
+ f = open('/home/elijah/Downloads/input13.txt')
+
+ np = f.readline().split()
+
+ n = int(np[0])
+
+ p = int(np[1])
+
+ astronaut = []
+
+ for _ in range(p):
+ astronaut.append(list(map(int, f.readline().rstrip().split())))
+
+ result = journeyToMoon(n, astronaut)
+
+ print(result)