[0-1 backpack TEMPLATE] poj 3624

First look at an unoptimized two-dimensional space DP:

#include <iostream>#include <cstdio>#include <cmath>#include <memory.h>using namespace std;const int maxn1=3500;const int maxn2=1300;int dp[maxn2][maxn2];//int dp[maxn2];int w[maxn1],v[maxn2];int m,n;int max(int x,int y){ return x>y?x:y;}int main(){    freopen("in.txt","r",stdin); while(~scanf("%d%d",&n,&m)) {  for(int i=1;i<=n;i++)   cin >> w[i] >> v[i]; } memset(dp,0,sizeof(dp)); int j; for(int i=1;i<=n;i++)    {        for(j=1;j<=m;j++)        {            if(j>=w[i])            dp[i][j]=max(dp[i-1][j],dp[i-1][j-w[i]]+v[i]);            else            dp[i][j] = dp[i-1][j];        }    } cout << dp[n][m] << endl; return 0;}

 

 

 

Improvement:

1. Two-Dimensional Optimization to one-dimensional

2. Write-down

#include <iostream>#include <cstdio>#include <cmath>#include <memory.h>using namespace std;const int maxn1=3500;const int maxn2=13000;int dp[maxn2],w[maxn1],v[maxn2];int m,n;int max(int a, int b){    if(a>b) return a ;    else return b ;}int main(){    freopen("in.txt","r",stdin);    freopen("out.txt","w",stdout); while(~scanf("%d%d",&n,&m)) {        memset(dp,0,sizeof(dp));  for(int i=1;i<=n;i++)   cin >> w[i] >> v[i];        int j;        for(int i=1;i<=n;i++)        {            for(j=m;j>=w[i];j--)            {                dp[j]=max(dp[j],dp[j-w[i]]+v[i]);                cout << j << " j "<< dp[j]<< endl;            }            cout <<endl;        }        cout << dp[m] << endl; } return 0;}

Give a group of data for ease of understanding:

6 J 4
5 J 4
4 J 4
3 J 4
2 J 4
1 J 4

6 J 10
5 J 10
4 J 10
3 J 10
2 J 6

6 J 22
5 J 18
4 J 16
3 J 12

6 J 23
5 J 19
4 J 16
3 J 12
2 J 7

23

 

 

 

 

Finally, the template is provided:

#include <iostream>#include <cstdio>#include <cmath>#include <memory.h>using namespace std;const int maxn1=3500;const int maxn2=13000;int dp[maxn2],w[maxn1],v[maxn1];int m,n;int max(int a, int b){    if(a>b) return a ;    else return b ;}int main(){    //freopen("in.txt","r",stdin);    while(~scanf("%d%d",&n,&m))    {        memset(dp,0,sizeof(dp));        for(int i=1;i<=n;i++)            cin >> w[i] >> v[i];        int j;        for(int i=1;i<=n;i++)            for(j=m;j>=w[i];j--)                dp[j]=max(dp[j],dp[j-w[i]]+v[i]);        cout << dp[m] << endl;    }    return 0;}

 

[0-1 backpack TEMPLATE] poj 3624