BZOJ 2073: [POI2004]PRZ [DP 状压]

#include <iostream>
#include <cstdio>
#include <cstring>
#include <algorithm>
#include <cmath>
using namespace std;
typedef long long ll;
const int N=18,S=(1<<16)+5,INF=1e9;
inline int read(){
char c=getchar();int x=0,f=1;
while(c<'0'||c>'9'){if(c=='-')f=-1;c=getchar();}
while(c>='0'&&c<='9'){x=x*10+c-'0';c=getchar();}
return x*f;
}
int m,n,a
,w
;
int f[S];
int main(){
//freopen("in","r",stdin);
m=read();n=read();
for(int i=0;i<n;i++){
a[i]=read(),w[i]=read();
f[1<<i]=a[i];
}
int All=1<<n;
memset(f,0x3f,sizeof(f));
f[0]=0;
for(int s=0;s<All;s++){
int sum=0,slow=0;
for(int i=0;i<n;i++)
if((1<<i)&s) sum+=w[i],slow=max(slow,a[i]);
if(sum<=m) f[s]=slow;
else for(int t=s&(s-1);t;t=s&(t-1)) f[s]=min(f[s],f[t]+f[s^t]);
}
printf("%d",f[All-1]);
}