PHP backtracking to solve 0-1 knapsack problem example analysis _ PHP Tutorial

PHP backtracking solves the problem of 0-1 backpacks. PHP backtracking to solve the 0-1 backpack problem example analysis this article mainly introduces the PHP backtracking method to solve the 0-1 backpack problem, the example analyzes the php backtracking method to solve the knapsack problem skills, some examples of solving the 0-1 backpack problem by using PHP backtracking

This article mainly introduces the PHP backtracking method to solve the problem of 0-1 backpacking. The example analyzes the php backtracking method to solve the problem of backpacking, which has some reference value. For more information, see

This article describes how PHP backtracking solves the problem of 0-1 backpacks. Share it with you for your reference. The specific analysis is as follows:

This code is written according to the pseudocode in the software designer tutorial;
The most troublesome thing is not to change the pseudo code to php, but to judge the array subscript starting from 0 and the corresponding subscript;
Write it with debugging output

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$ V_arr = array (, 33 ); $ W_arr = array ); $ N = count ($ w_arr ); // Test output Var_dump (bknap1 (110 )); // Var_dump (bound (7,110 )); Function bound ($ v, $ w, $ k, $ W_total ){ Global $ v_arr, $ w_arr, $ n; $ B = $ v; $ C = $ w; // Var_dump ($ W_total); var_dump ($ n); var_dump ($ k); var_dump ($ v); var_dump ($ w ); // Die; For ($ I = $ k + 1; $ I <$ n; $ I ++ ){ $ C = $ c + $ w_arr [$ I]; // Var_dump ($ W_total); var_dump ($ c ); If ($ c <$ W_total) $ B + = $ v_arr [$ I]; Else { // Var_dump (1-($ c-$ W_total)/$ w_arr [$ I]) * $ v_arr [$ I]); $ B = $ B + (1-($ c-$ W_total)/$ w_arr [$ I]) * $ v_arr [$ I]; Return $ B; } } /* Var_dump ('------ bound head '); Var_dump ($ k ); Var_dump ($ B ); Var_dump ('------ bound end ');*/ Return $ B; } Function bknap1 ($ W_total ){ Global $ v_arr, $ w_arr, $ n; $ Cw = $ cp = 0; $ K = 0; $ Fp =-1; While (true ){ While ($ k <$ n & $ cw + $ w_arr [$ k] <= $ W_total ){ $ Cw + = $ w_arr [$ k]; $ Cp + = $ v_arr [$ k]; $ Y_arr [$ k] = 1; $ K + = 1; } // Var_dump ($ cw); var_dump ($ cp); var_dump ($ Y_arr); var_dump ($ k); var_dump ($ n ); If ($ k = $ n ){ $ Fp = $ cp; $ Fw = $ cw; $ K = $ n-1; $ X_arr = $ Y_arr; // Bound ($ cp, $ cw, $ k, $ W_total ); // Var_dump (bound ($ cp, $ cw, $ k, $ W_total), $ fp, $ k); die; // Var_dump ($ fp); var_dump ($ fw); var_dump ($ Y_arr); var_dump ($ k); var_dump ($ n ); } Else { $ Y_arr [$ k] = 0; } // Var_dump ($ Y_arr); var_dump ($ k); var_dump ($ n); // die; // Var_dump (bound ($ cp, $ cw, $ k, $ W_total), $ fp); die; While (bound ($ cp, $ cw, $ k, $ W_total) <= $ fp) { While ($ k> = 0 & $ Y_arr [$ k]! = 1 ){ $ K-= 1; } If ($ k <0) { Return $ X_arr; } Var_dump ($ k ); $ Y_arr [$ k] = 0; $ Cw-= $ w_arr [$ k]; $ Cp-= $ v_arr [$ k]; } $ K + = 1; } } ?>

I hope this article will help you with php programming.

Ghost This article mainly introduces PHP backtracking to solve the problem of 0-1 backpacks. Examples of php backtracking to solve the problem of backpacks are analyzed...