POJ 2976 Dropping tests（普通01分数规划）

就是一道裸的题目，刚开始学试了2种写法，具体的方法学习可以看http://www.cnblogs.com/perseawe/archive/2012/05/03/01fsgh.html

二分代码：

//#pragma comment(linker, "/STACK:102400000,102400000")
#include<cstdio>
#include<ctype.h>
#include<algorithm>
#include<iostream>
#include<cstring>
#include<vector>
#include<cstdlib>
#include<stack>
#include<cmath>
#include<queue>
#include<set>
#include<map>
#include<ctime>
#include<string.h>
#include<string>
#include<sstream>
#include<bitset>
using namespace std;
#define ll long long
#define ull unsigned long long
#define eps 1e-7
#define NMAX 1000005
#define MOD 1000000007
#define lson l,mid,rt<<1
#define rson mid+1,r,rt<<1|1
#define PI acos(-1)
template<class T>
inline void scan_d(T &ret)
{
char c;
int flag = 0;
ret=0;
while(((c=getchar())<'0'||c>'9')&&c!='-');
if(c == '-')
{
flag = 1;
c = getchar();
}
while(c>='0'&&c<='9') ret=ret*10+(c-'0'),c=getchar();
if(flag) ret = -ret;
}
ll a[1005],b[1005];
double d[1005];
int main()
{
#ifdef GLQ
freopen("input.txt","r",stdin);
// freopen("o4.txt","w",stdout);
#endif // GLQ
int n,k;
while(~scanf("%d%d",&n,&k) && n+k)
{
for(int i = 1; i <= n; i++) scanf("%I64d",&a[i]);
for(int i = 1; i <= n; i++) scanf("%I64d",&b[i]);
double l = 0,r = 1,mid;
while(abs(r-l) > eps)
{
mid = (l+r)/2;
for(int i = 1; i <= n; i++) d[i] = a[i]-mid*b[i];
sort(d+1,d+1+n);
double tmp=0;
for(int i = k+1; i <= n; i++) tmp += d[i];
// cout<<tmp<<" "<<l<<" "<<r<<" "<<mid<<endl;
if(tmp >= 0) l = mid;
else r = mid;
}
int ans = l*100.0+0.5;
printf("%d\n",ans);
}
return 0;
}Dinkelbach写法：
//#pragma comment(linker, "/STACK:102400000,102400000")
#include<cstdio>
#include<ctype.h>
#include<algorithm>
#include<iostream>
#include<cstring>
#include<vector>
#include<cstdlib>
#include<stack>
#include<cmath>
#include<queue>
#include<set>
#include<map>
#include<ctime>
#include<string.h>
#include<string>
#include<sstream>
#include<bitset>
using namespace std;
#define ll long long
#define ull unsigned long long
#define eps 1e-7
#define NMAX 1000005
#define MOD 1000000007
#define lson l,mid,rt<<1
#define rson mid+1,r,rt<<1|1
#define PI acos(-1)
template<class T>
inline void scan_d(T &ret)
{
char c;
int flag = 0;
ret=0;
while(((c=getchar())<'0'||c>'9')&&c!='-');
if(c == '-')
{
flag = 1;
c = getchar();
}
while(c>='0'&&c<='9') ret=ret*10+(c-'0'),c=getchar();
if(flag) ret = -ret;
}
ll a[1005],b[1005];
struct node
{
double ha;
int pos;
bool operator < (const node &t) const
{
return ha < t.ha;
}
};
node d[1005];
int main()
{
#ifdef GLQ
freopen("input.txt","r",stdin);
// freopen("o4.txt","w",stdout);
#endif // GLQ
int n,k;
while(~scanf("%d%d",&n,&k) && n+k)
{
for(int i = 1; i <= n; i++) scanf("%I64d",&a[i]);
for(int i = 1; i <= n; i++) scanf("%I64d",&b[i]);
double ans=100,L = 0;
ll p,q;
while(abs(L-ans) > eps)
{
ans = L;
for(int i = 1; i <= n; i++)
{
d[i].ha = a[i]-L*b[i]/100.0;
d[i].pos = i;
}
sort(d+1,d+1+n);
p = q = 0;
for(int i = k+1; i <= n; i++)
{
p += a[d[i].pos];
q += b[d[i].pos];
}
L = (double)p/q*100.0;
}
printf("%.0lf\n",ans);
}
return 0;
}