0 1背包问题之leetcode总结
作者:互联网
直接上代码吧,可以递归解决也可以非递归解决。
import java.util.LinkedList; public class Main{ /* 由dp[i - 1][j]推出,即背包容量为j,里面不放物品i的最大价值,此时dp[i][j]就是dp[i - 1][j] 由dp[i - 1][j - weight[i]]推出,dp[i - 1][j - weight[i]] 为背包容量为j - weight[i]的时候不放物品i的最大价值, 那么dp[i - 1][j - weight[i]] + value[i] (物品i的价值),就是背包放物品i得到的最大价值 */ static void test_2_wei_bag_problem1() { int[] weight = {1, 3, 4}; int[] value = {15, 20, 30}; int bagWeight = 4;//包的容量 bagWeight = 6;//包的容量 weight=new int[]{1,2,3,4,5}; value=new int[]{2,4,4,5,6}; bagWeight = 100;//包的容量 weight=new int[]{77,22,29,50,99}; value=new int[]{92,22,87,46,90}; // 二维数组 int[][] dp = new int[weight.length][bagWeight + 1]; // 初始化 //初始化第一列 weight[0] for (int i = 1; i < dp[0].length; i++) { if (i >= weight[0]) { dp[0][i] = value[0]; } } //容量为0 for (int i = 0; i < dp.length; i++) { dp[i][0] = 0; } // weight数组的大小 就是物品个数 for (int i = 1; i < weight.length; i++) { // 遍历物品 for (int j = 1; j <= bagWeight; j++) { // 遍历背包容量 if (j < weight[i]) dp[i][j] = dp[i - 1][j]; else dp[i][j] = Math.max(dp[i - 1][j], dp[i - 1][j - weight[i]] + value[i]); } } System.out.println(dp[weight.length - 1][bagWeight]); } public static void test_2_wei_bag_problem0() { int[] weight = {1, 3, 4}; int[] value = {15, 20, 30}; int bagWeight = 6;//包的容量 bagWeight = 6; weight=new int[]{1,2,3,4,5}; value=new int[]{2,4,4,5,6}; bagWeight = 100;//包的容量 weight=new int[]{77,22,29,50,99}; value=new int[]{92,22,87,46,90}; helper(weight,value,bagWeight,0); System.out.println(sum); } public static LinkedList<Integer> list = new LinkedList<>(); public static int sum = 0; public static void helper(int[] weight, int[] value, int bagWeight, int index) { if (index >= weight.length) return; if (bagWeight >= 0) { int cnt = 0; for (Integer i : list) { cnt+=i; } sum=Math.max(sum,cnt); } list.add(value[index]); helper(weight, value, bagWeight - weight[index], index + 1); list.pollLast(); helper(weight, value, bagWeight, index + 1); } public static void main(String[] args) { test_2_wei_bag_problem1(); test_2_wei_bag_problem0(); } }
标签:总结,index,背包,weight,int,value,bagWeight,leetcode,dp 来源: https://www.cnblogs.com/clarencezzh/p/15059064.html