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57 lines
1.6 KiB
Java
57 lines
1.6 KiB
Java
package com.jwetherell.algorithms.mathematics;
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import java.util.ArrayList;
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import java.util.List;
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public class Knapsack {
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public static final int[] zeroOneKnapsack(int[] values, int[] weights, int capacity) {
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if (weights.length != values.length)
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return null;
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int height = weights.length + 1; // weights==values
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int width = capacity + 1;
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int[][] output = new int[height][width];
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for (int i = 1; i < height; i++) {
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int index = i - 1;
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for (int j = 1; j < width; j++) {
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if (i == 0 || j == 0) {
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output[i][j] = 0;
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} else {
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if (weights[index] > j) {
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output[i][j] = output[i - 1][j];
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} else {
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int v = values[index] + output[i - 1][j - weights[index]];
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output[i][j] = Math.max(output[i - 1][j], v);
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}
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}
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}
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}
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List<Integer> list = new ArrayList<Integer>();
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int i = height - 1;
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int j = width - 1;
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while (i != 0 || j != 0) {
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int current = output[i][j];
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int above = output[i - 1][j];
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if (current == above) {
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i -= 1;
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} else {
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i -= 1;
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j -= weights[i];
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list.add(i);
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}
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}
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int count = 0;
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int[] result = new int[list.size()];
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for (Object obj : list.toArray()) {
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if (obj instanceof Integer)
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result[count++] = (Integer) obj;
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}
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return result;
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}
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}
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