Can you write a GAMS CODE according to these question and answer ? Thank you so much.

I ONLY NEED GAMS CODES !!!!

Given a number of cities and the costs of traveling from any city to any other city, what is the cheapest round-trip route (tour) that visits each city once and then returns to the starting city? This problem is called the traveling salesperson problem (TSP). An itinerary that begins and ends at the same city and visits each city once is called a tour. Suppose there are N cities. Let cij = Distance from city i to city j (for ij) and Let cii = M (a very large number relative to actual distances) Also define xij as a 0-1 variable as follows: xij = 1 if s/he goes from city i to city j;

Xij = 0 otherwise The formulation of the TSP is: min i; Cijkij s.t. Litij = 1 for all j 2; Xij = 1 for all i Ui ; + Nxij N-1 for i #j; i, j> 1 All Xij = 0 or 1 All u; 20 The first set of constraints ensures that s/he arrives once at each city. The second set of constraints ensures that s/he leaves each city once. The third set of constraints ensure the following: Any set of xi's containing a subtour will be infeasible Any set of Xi's that forms a tour will be feasible Ui - u; + Nxij N-1 for i #j; i,j > 1 Assume N=5 Subtours: 1-5-2-1, 3-4-3 ??? Choose the subtour that does not contain city 1: u3 - U4+ 5 34 34 U4 - U3 + 5 X43 5 4 5 (X34 + X43) = 8 This rules out the possibility that X34 = X43 = 1 The formulation of an IP whose solution will solve a TSP becomes unwieldy and inefficient for large TSPs. When using branch and bound methods to solve TSPs with many cities, large amounts of computer time may be required. For this reason, heuristics, which quickly lead to a good (but not necessarily optimal) solution to a TSP, are often used. Xij = 0 otherwise The formulation of the TSP is: min i; Cijkij s.t. Litij = 1 for all j 2; Xij = 1 for all i Ui ; + Nxij N-1 for i #j; i, j> 1 All Xij = 0 or 1 All u; 20 The first set of constraints ensures that s/he arrives once at each city. The second set of constraints ensures that s/he leaves each city once. The third set of constraints ensure the following: Any set of xi's containing a subtour will be infeasible Any set of Xi's that forms a tour will be feasible Ui - u; + Nxij N-1 for i #j; i,j > 1 Assume N=5 Subtours: 1-5-2-1, 3-4-3 ??? Choose the subtour that does not contain city 1: u3 - U4+ 5 34 34 U4 - U3 + 5 X43 5 4 5 (X34 + X43) = 8 This rules out the possibility that X34 = X43 = 1 The formulation of an IP whose solution will solve a TSP becomes unwieldy and inefficient for large TSPs. When using branch and bound methods to solve TSPs with many cities, large amounts of computer time may be required. For this reason, heuristics, which quickly lead to a good (but not necessarily optimal) solution to a TSP, are often used