[POJ2392] Space Elevator

题意：

传送门

题解：

多重背包

转01背包，二进制分下组，压压常，轻松水过......

#include<iostream>
#include<cstdio>
#include<cstdlib>
#include<cstring>
#include<algorithm>
#include<cmath>
#define ll long long
#define RG register
#define N 1650
#define M 40010
using namespace std;

int a[N],b[N],dfn[N],dp[M];

inline int gi() {
  int x=0,o=1; char ch=getchar();
  while(ch!='-' && (ch<'0' || ch>'9')) ch=getchar();
  if(ch=='-') o=-1,ch=getchar();
  while(ch>='0' && ch<='9') x=x*10+ch-'0',ch=getchar();
  return o*x;
}

inline bool cmp(int x, int y) {
  return b[x]<b[y];
}

int main() {
  RG int n=gi(),m=0,cnt=0;
  for(RG int i=1; i<=n; i++) {
    int x=gi(),y=gi(),z=gi(),k;
    for(RG int j=1; z; j<<=1) {
      k=min(j,z),z-=k;
      a[++cnt]=k*x,b[cnt]=y;
    }
    m=max(m,y);
  }
  for(RG int i=1; i<=cnt; i++) dfn[i]=i;
  sort(dfn+1,dfn+cnt+1,cmp);
  dp[0]=1;
  for(RG int i=1; i<=cnt; i++) {
    int u=dfn[i];
    for(RG int j=b[u]; j>=0; j--) {
      if(j-a[u]>=0) {
	dp[j]|=dp[j-a[u]];
      }
    }
  }
  for(int i=m; i>=0; i--) {
    if(dp[i]) {
      printf("%d
", i);
      break;
    }
  }
  return 0;
}