Optimize my code by converting Recursion to Iteration or any other method

Question

Question: Given the graph where vertices represent worksites and edges represent pairs of sites that must be able to communicate securely. what are the fewest worksites that can have the securely-monitoring nodes to guarantee that each pair has atleast one. 

My Solution:

n, m = map(int, input().split())

p = [0] * m

target = 2 ** m - 1

def solve(i, subset, size):if subset == target:

return size

if i == n:

return n + 1return min(solve(i + 1, subset, size),

solve(i + 1, subset | p[i], size + 1))

for i in range(m):

u, v = map(int, input().split())

p[u] += 2 ** i

p[v] += 2 ** i

print(solve(0, 0, 0))

Answer 1

This involves changing the space-time complexity of the program.