# receiving “None” as result in CVXPY problem solver

Trying to solve TSP as linear programming task using cvxpy and have problem with this. It is my first experience so thanks for help. As a result I want to have matrix with 0 and 1 that shows every next city for salesman.

need to use exactly cvxpy

cvxpy website

thanks for help

```import cvxpy as cp
import numpy as np

np.random.seed(1)
N = 10
distances = np.random.rand(N, N)

x = cp.Variable((N, N), boolean=True)
u = cp.Variable(N, integer=True)

constraints = []

for j in range(N):
indices = list(range(0, j)) + list(range(j + 1, N))
constraints.append(cp.sum(x[indices, j]) == 1)
for i in range(N):
indices = list(range(0, i)) + list(range(i + 1, N))
constraints.append(cp.sum(x[i, indices]) == 1)
for i in range(1, N):
for j in range(1, N):
if i != j:
constraints.append(u[i] - u[j] + N*x[i, j] <= N-1)

for i in range(N):
for j in range(N):
if i != j:
сost += (x[i,j]*distances[i,j])

prob = cp.Problem(cp.Minimize(cost), constraints)
prob.solve()
print(prob.value)
```