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The garage sale problem (courtesy of Professor Lofti Zadeh). On a given Sunday morning, there are n garage sales going on, g1,g2,g3............gn. For each garage sale gj, you have an estimate of its value to you, vj. For any two garage sales you have an estimate of the transportation cost dijof getting from gito gj. You are also given the costs d0jand dj0of going between your home and each garage sale. You want to find a tour of a subset of the given garage sales, starting and ending at home, that maximizes your total benefit minus your total transportation costs. Give an algorithm that solves this problem in time O(n22n).

(Hint: This is closely related to the traveling salesman problem.)

Short Answer

Expert verified

This problem is identical to that of Traveling salesman problem where need to add one variant to it, that is to find relevant benefit by computing optimal distance. This problem is solved by dynamic programming approach.

Step by step solution

01

Dynamic programming approach.

In dynamic programming there are all possibilities and more time as compared to greedy programming. and the Dynamic programming approach always gives the accurate or correct answer. In dynamic programming have to compute only distinct function call because as soon as compute and store in one data structure so that after this reuse afterward if it is needed.

02

Algorithm for traveling salesman problem.

Let G be the garage is g1,g2,g3...........gnand the P (G,j) is the gain function. Also assume that 'j'is the last garage we will visit before we reach back to origin.

Given: d0jis the transportation cost from traveling gitogjto . Then compute Maximum of (gj-d0j)

Ifvi is the gain from garage gi. Then, the base case, P0,j=vj-d0j. This means the garage salesman have travel from origin is the starting point to garagegj.

, This is the recursive equation.

PG,j=maxPG-gi,i+pj-dij

P0,1=VJ-d0jfors=2tonPG,1=∞forj=1tonPG,1=maxPG-gii+pj-dijreturnPG,j

Hence by using, the algorithm which is closely related to the traveling salesman problem in which the shortest distance is to find between the starting node as source node to the end node called as destination node. For each garage sale gj, you have an estimate of its value to you,vj. For any two garage sales you have an estimate of the transportation cost dijof getting from gitogj.tour of a subset of the given garage sales, starting and ending at home is evaluated.

So, In this problem, the number of sub problems are n22nand to solve each sub problem, it takes time. So, total complexity is On22n.

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