0/1背包一般解法有:(1)动态规划(包体积一般不大)(2)dfs+剪枝(物品总数一般100以下)
HDU-2062
#include <iostream>
#include <cstdio>
#include <cstring>
#include <algorithm>
using namespace std;
int dp[1005],value[1005],V[1005];
int main()
{
int T;
scanf("%d",&T);
while(T--)
{
memset(dp,0,sizeof dp);
int n,v;
scanf("%d%d",&n,&v);
for(int i = 0; i < n; i++)
scanf("%d",&value[i]);
for(int i = 0; i < n; i++)
scanf("%d",&V[i]);
for(int i = 0; i < n; i++)
for(int j = v; j >= V[i]; j--)
dp[j] = max(dp[j],dp[j-V[i] ]+value[i]);
printf("%d\n",dp[v]);
}
return 0;
}
HDU-2546
#include <iostream>
#include <cstdio>
#include <cstring>
#include <algorithm>
using namespace std;
const int maxn = 1005;
int dp[maxn],a[maxn];
int main()
{
int n;
while(~scanf("%d",&n)&&n)
{
memset(dp,0,sizeof dp);
for(int i = 0; i < n; i++)
scanf("%d",&a[i]);
sort(a,a+n);
int money;
scanf("%d",&money);
if(money < 5)
printf("%d\n",money);
else
{
for(int i = 0; i < n-1; i++)
for(int j = money-5; j >= a[i]; j--)
dp[j] = max(dp[j],dp[j-a[i]]+a[i]);
printf("%d\n",money-dp[money-5]-a[n-1]);
}
}
return 0;
}
HDU3466
#include <iostream>
#include <cstdio>
#include <cstring>
#include <algorithm>
using namespace std;
int dp[5005];
struct node
{
int p,q,v;
}spe[505];
bool cmp(node a,node b)
{
return (a.p-a.q) > (b.p-b.q);
}
int main()
{
int n,m;
while(~scanf("%d%d",&n,&m))
{
for(int i =0 ;i < n; i++)
scanf("%d%d%d",&spe[i].p,&spe[i].q,&spe[i].v);
sort(spe,spe+n,cmp);
memset(dp,0,sizeof dp);
for(int i = 0; i < n; i++)
for(int j = m; j >= spe[i].q; j--)
dp[j] = max(dp[j],dp[j-spe[i].p]+spe[i].v);
printf("%d\n",dp[m]);
}
return 0;
}
UVA-12563
#include <iostream>
#include <cstdio>
#include <cstring>
using namespace std;
int a[55],dp[55*180];
int main()
{
int n,time,T,Case = 1;
scanf("%d",&T);
while(T--)
{
scanf("%d%d",&n,&time);
for(int i = 0; i < n; i++)
scanf("%d",&a[i]);
memset(dp,-1,sizeof dp);
dp[0] = 0;
int s = 0;
for(int i = 0; i < n; i++)
for(int j = time-1; j >= a[i]; j--)
dp[j] = max(dp[j],dp[j-a[i] ]+1);
for(int i = 0; i < time; i++)
if(dp[i] >= dp[s])
s = i;
printf("Case %d: %d %d\n",Case++,dp[s]+1,s+678);
}
}
//我尝试着用dfs加剪枝写,但没有采取合理的剪枝方法,超时
/*
#include <iostream>
#include <cstdio>
#include <cstring>
#include <algorithm>
using namespace std;
int a[55];
int n,Time,cnt = 0,sum = 0,total = 0,sum1 = 0;
void dfs(int x,int t,int sum1,int total)
{
for(int i = x; i < n; i++)
{
if(t-a[i] <= 0)
{
if(sum1 > sum)
{
sum = sum1;
cnt = total;
}
return ;
}
dfs(x+1,t-a[i],sum1+a[i],total+1);
}
}
int main()
{
int T,Case = 1;
scanf("%d",&T);
while(T--)
{
//memset(a,-1,sizeof a);
scanf("%d%d",&n,&Time);
for(int i = 0; i < n; i++)
scanf("%d",&a[i]);
sort(a,a+n);
dfs(0,Time,0,0);
printf("Case %d: %d %d\n",Case++,cnt+1,sum+678);
}
return 0;
}*/
/*
2
10 100
9 20 25 40 43 47 52 66 73 90
*/