Case study of PHP greedy algorithm for solving the 0-1 knapsack problem

This article mainly introduces the PHP greedy algorithm to solve the 0-1 knapsack problem. The example analyzes the principles of the greedy algorithm and the implementation skills of the knapsack problem. For more information, see

This article mainly introduces the PHP greedy algorithm to solve the 0-1 knapsack problem. The example analyzes the principles of the greedy algorithm and the implementation skills of the knapsack problem. For more information, see

This article describes how to solve the 0-1 knapsack problem by using the PHP greedy algorithm. Share it with you for your reference. The specific analysis is as follows:

The greedy algorithm solves the problem of 0-1 backpacks. The global optimal solution is obtained through the local optimal solution! This solution is more flexible than dynamic planning!

// Class tanxin {public $ weight; public $ price; public function _ construct ($ weight = 0, $ price = 0) {$ this-> weight = $ weight; $ this-> price = $ price ;}// generate data $ n = 10; for ($ I = 1; $ I <= $ n; $ I ++) {$ weight = rand (); $ price = rand ); $ x [$ I] = new tanxin ($ weight, $ price);} // output result function display ($ x) {$ len = count ($ x ); foreach ($ x as $ val) {echo $ val-> weight, '', $ val-> price; echo'
';}} // Sort the function tsort (& $ x) {$ len = count ($ x); for ($ I = 1; $ I <= $ len; $ I ++) {for ($ j = 1; $ j <= $ len-$ I; $ j ++) {$ temp = $ x [$ j]; $ res = $ x [$ j + 1]-> price/$ x [$ j + 1]-> weight; $ temres = $ temp-> price/$ temp-> weight; if ($ res> $ temres) {$ x [$ j] = $ x [$ j + 1]; $ x [$ j + 1] = $ temp ;}}// greedy algorithm function tanxin ($ x, $ totalweight = 50) {$ len = count ($ x); $ allprice = 0; for ($ I = 1; $ I <= $ len; $ I ++) {if ($ x [$ I]-> weight> $ totalweight) break; else {$ allprice + = $ x [$ I]-> price; $ totalweight = $ totalweight-$ x [$ I]-> weight;} if ($ I <$ len) $ allprice + = $ x [$ I]-> price * ($ totalweight/$ x [$ I]-> weight); return $ allprice;} tsort ($ x ); // display ($ x) by non-incrementing order; // The echo '0-1 backpack's optimal solution is: '; echo tanxin ($ x );

I hope this article will help you with php programming.

,