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2. Weighing with weights - Lanqiao Cloud Course (lanqiao.cn)

Ideas

The core idea of ​​dynamic programming is to decompose the problem into smaller sub-problems and store the solutions of the sub-problems to avoid repeated calculations.

Arraysdp[i][j]Before useiThe weight that can be weighed isjquantity

The update process is as follows:

1. Initialization: dp[0][0] = 0;

2. For each weight wi:

 

ac code

#include<bits/stdc++.h>
typedef long long ll;
 
#define IOS ios::sync_with_stdio(0),cin.tie(0),cout.tie(0)
const ll M=2e5+10;
const int N=110;
int dp[N][M]={0};
using namespace std;
 
int main()
{
    IOS;
    int n,num=0;
    cin>>n;
    int w[N];
    ll ans=0;
    for(int i=1;i<=n;i++)
    {
        cin>>w[i];
        num+=w[i];
    }
    dp[0][0]=1;
    for(int i=1;i<=n;i++)
    {
        for(int j=0;j<=num;j++)
        {
            dp[i][j] =  dp[i-1][j] + dp[i-1][abs(j-w[i])] + dp[i-1][j+w[i]];
            //cout<<dp[i][j]<<" ";
        }
        //cout<<endl;
    }
 
    for(int i=1;i<=num;i++)
    {
        if(dp[n][i]) ans++;
    }
    cout<<ans;
    return 0;
}