揹包問題的 javascript和java 實現
阿新 • • 發佈：2018-10-31
簡述：
一個揹包，總載重量限定
提供各種質量及相應價值的物品， 提供一個價值最優的裝包選擇
參考： http://www.importnew.com/13072.html
<!DOCTYPE html> <head> <meta charset="utf-8"> <script type = "text/javascript"> var total = 10; var OBJ_NUM = 4; var weights = []; var values = []; var matrix = []; /**** init weights ****/ weights.push(0); // defualt 0 weights.push(5); weights.push(4); weights.push(6); weights.push(3); /**** init values ****/ values.push(0); // default 0 values.push(10); values.push(40); values.push(30); values.push(50); /** init row 0 value as ZERO **/ for(var i=0; i<(OBJ_NUM+1)*(total+1); i++) matrix.push(0); var X_WIDTH = total + 1; /**** calculate ****/ for(var y=1; y<=OBJ_NUM; y++){ for(var x=1; x<=total; x++){ if(x >= weights[y]){ // 添加了當前物品的價值 var addedValue = matrix[(y - 1) * X_WIDTH + (x - weights[y])] + values[y]; matrix[y*X_WIDTH + x] = Math.max(addedValue, matrix[(y - 1) * X_WIDTH + x]); }else{ matrix[y*X_WIDTH + x] = matrix[(y-1) * X_WIDTH + x]; } } } for(var y=1; y<=OBJ_NUM; y++){ for(var x=1; x<=total; x++){ document.write(matrix[y*X_WIDTH + x] + "\t"); } document.write("</br>"); } document.write("最優解（揹包的總value值最大）為： " + matrix[(OBJ_NUM+1)*X_WIDTH - 1]); </script> </head> </html>
輸出：
下面是Java的實現
package com.anialy.test.packnage; /** * Package: com.anialy.test.packnage * 參考： http://www.importnew.com/13072.html * */ public class PackageProblem { // 物品數量 private static final int NUM = 4; // 物品質量, 0為佔位符 private static int wt[] = new int[]{0, 5, 4, 6, 3}; // 物品價值, 0為佔位符 private static int val[] = new int[]{0, 10, 40, 30, 50}; // 揹包容量 private static final int TOTAL = 10; private static final int X_WIDTH = TOTAL + 1; private static int process(){ int calc[] = new int[X_WIDTH * (NUM + 1)]; for(int y=0; y<=NUM; y++) for(int x=0; x<=TOTAL; x++) calc[y*X_WIDTH + x] = 0; for(int y=1; y<=NUM; y++){ for(int x=1; x<=TOTAL; x++){ if(x >= wt[y]){ calc[y*X_WIDTH + x] = Math.max( val[y] + calc[(y-1)*X_WIDTH + (x-wt[y])] , calc[(y-1)*X_WIDTH + x]); }else{ calc[y*X_WIDTH + x] = calc[(y-1)*X_WIDTH + x]; } } } for(int y=1; y<=NUM; y++){ for(int x=1; x<=TOTAL; x++){ System.out.format("%3d ", calc[y*X_WIDTH + x]); } System.out.printf("\n"); } // 返回最後一個 return calc[(NUM+1)*X_WIDTH - 1]; } public static void main(String[] args) { System.out.printf("\n optimum value: %d", process()); } }