01背包问题

#include<iostream>
#include<vector>
using namespace std;
//01背包问题
void test_bag_problem(){
    vector<int> weight={1,3,4};
    vector<int> value={15,20,30};
    int bagweight=4;//背包容量
    //****************编写代码*************//
  //*************************************//
    //输出dp
    cout<<dp[bagweight]<<endl;
}
int main(){
    test_bag_problem();
    system("pause");
    return 0;
}

void test_2_wei_bag_problem(){
    vector<int> weight={1,3,4};
    vector<int> value={15,20,30};
    int bagweight=4;//背包容量
    vector<vector<int>> dp(weight.size(),vector<int>(bagweight+1,0));
    for(int j=weight[0];j<=bagweight;j++){
        dp[0][j]=value[0];
    }
    for(int i=1;i<weight.size();i++){
        for(int j=0;j<=bagweight;j++){
            if(j<weight[i]) dp[i][j]=dp[i-1][j];
            else dp[i][j]=max(dp[i-1][j],dp[i-1][j-weight[i]]+value[i]);
        }
    }
    for(vector<int> vec:dp){
        for(int val:vec){
            cout<<val<<" ";
        }
        cout<<endl;
    }
}
int main(){
    test_2_wei_bag_problem();
    system("pause");
    return 0;
}

void test_1_wei_bag_problem() {
    vector<int> weight = {1, 3, 4};
    vector<int> value = {15, 20, 30};
    int bagWeight = 4;
    // 初始化
    vector<int> dp(bagWeight + 1, 0);
    for(int i = 0; i < weight.size(); i++) { // 遍历物品
        for(int j = bagWeight; j >= weight[i]; j--) { // 遍历背包容量
            dp[j] = max(dp[j], dp[j - weight[i]] + value[i]);
        }
    }
    cout << dp[bagWeight] << endl;
}
int main() {
    test_1_wei_bag_problem();
}

public class Main {
    public static void main(String[] args) {
        int[] weight={1,3,4};
        int[] value={15,20,30};
        int bagWeight=4;
        int[] dp=new int[bagWeight+1];
        for(int i=0;i<weight.length;i++){
            for(int j=bagWeight;j>=weight[i];j--){
                dp[j]=Math.max(dp[j],dp[j-weight[i]]+value[i]);
            }
        }
        System.out.println(dp[bagWeight]);
    }
}