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Number_of_Operations_to_Make_Network_Connected.py
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Number_of_Operations_to_Make_Network_Connected.py
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def makeConnected(self, n: int, connections: List[List[int]]) -> int:
A = [0]*n # Stores the component number of each node
N = [] # stores neighbours of each node
for i in range(n):
N.append([])
for i in connections:
N[i[0]].append(i[1])
N[i[1]].append(i[0])
#N : ith array has all neighbours of ith node
count = 0
extra = 0
stack = []
# Applying DFS
i = j = 0
index = 0
while index < n:
if len(stack) == 0:
if A[index] == 0:
count += 1
stack.append([index,0])
A[index] = count
index += 1
else:
i,j = stack[-1][0],stack[-1][1]
if j >= len(N[i]):
stack.pop()
if stack:
stack[-1][1] += 1
else:
if A[N[i][j]] == 0:
stack.append([N[i][j],0])
A[N[i][j]] = count
elif A[N[i][j]] == count:
if N[i][j] != stack[-2][0]:#Checking for existence of a cycle
extra += 1
N[N[i][j]].remove(i)
stack[-1][1] += 1
if extra >= count - 1:
return count - 1
else:
return -1