POJ3624

来源：互联网发布：淘宝分流最多设置多少编辑：程序博客网时间：2024/06/05 19:32

0-1背包，动态规划学习

import java.io.FileNotFoundException;import java.util.Scanner;public class Main {//Memory Limit Exceeded    static int r;    static int c;    static int[] w;    static int[] v;    // static int mv[][];//max value    static int[][] mv;    public static void main(String[] args) throws FileNotFoundException {        // File file=new File("c:/data.txt");        // Scanner cin=new Scanner(file);        Scanner cin = new Scanner(System.in);        r = cin.nextInt();// r件物品        c = cin.nextInt();// 袋子大小        mv = new int[r + 1][c + 1];        w = new int[r + 1];// 第i件物品的重量        v = new int[r + 1];// 第i件物品的价值        for (int i = 1; i <= r; i++) {// input weight & value            w[i] = cin.nextInt();            v[i] = cin.nextInt();        }        for (int i = 1; i <= r; i++) {            for (int j = 1; j <= c; j++) {// j袋子剩余容量                if (j >= w[i]) {// 装得下                    int a = mv[i - 1][j];// 不装第i件物品                    int b = mv[i - 1][j - w[i]] + v[i];// 装第i件物品                    mv[i][j] = max(a, b);                } else {                    mv[i][j] = mv[i - 1][j];                }            }        }        System.out.println(mv[r][c]);    }    static int max(int a, int b) {        return a > b ? a : b;    }}

优化空间

import java.io.FileNotFoundException;import java.util.Scanner;public class Main {//poj上类名必须为Main    static int r;    static int c;    static int[] w;    static int[] v;    // static int mv[][];//max value    static int[] mv;    public static void main(String[] args) throws FileNotFoundException {        // File file=new File("c:/data.txt");        // Scanner cin=new Scanner(file);        Scanner cin = new Scanner(System.in);        r = cin.nextInt();// r件物品        c = cin.nextInt();// 袋子大小        mv = new int[c + 1];        w = new int[r + 1];// 第i件物品的重量        v = new int[r + 1];// 第i件物品的价值        for (int i = 1; i <= r; i++) {// input weight & value            w[i] = cin.nextInt();            v[i] = cin.nextInt();        }        for (int i = 1; i <= r; ++i) {            for (int j = c; j >= w[i]; --j) {// j袋子剩余容量                int a = mv[j - w[i]] + v[i];// 加上第i件物品的最大价值                int b = mv[j];// 不加第i件物品的最大价值                mv[j] = max(a, b);            }        }        System.out.println(mv[c]);    }    static int max(int a, int b) {        return a > b ? a : b;    }}

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