poj1837 (Balance)

Title Address: Balance

Main topic:

There is a balance, there are several hooks on both sides of the balance, a total of C hooks, there is a G hook code, the hook code all hanging to the hook so that the balance of the total number of methods. The Libra can be viewed as a horizontal axis with an x-axis of 0 points as the balance point.

Problem Solving Ideas:

DP: The most extreme balance is that all objects hang at the far end, so the maximum balance is j=15*20*25=7500. In principle there should be dp[1~20][-7500 ~ 7500]. Converted to 01 backpack, where I represents the first I hook to reach the J-balance of all cases, because it is a balance so the balance of the middle value is the result of the balance, because there is a negative DP conversion to dp[1~20][0 ~ 16000]. DP[G][8000] can, remember initialization, initialization can only be initial dp[0][8000], if all hooks to 0 of the balance of the initial impact on the results.

Can be set Dp[i-1][j]=num, then for DP[I][J] There are two kinds of decision, is to choose where the first weight of the position or not put. So Dp[i][j]+=dp[i-1][j-pos[k]*weight[i]]. Of course the precondition is j>=pos[k]*weight[i].

Code:

1#include <algorithm>2#include <iostream>3#include <sstream>4#include <cstdlib>5#include <cstring>6#include <cstdio>7#include <string>8#include <bitset>9#include <vector>Ten#include <queue> One#include <stack> A#include <cmath> -#include <list> -#include <map> the#include <Set> - using namespaceStd/***************************************/ - #definell Long Long - #defineInt64 __int64/***************************************/ + Const intINF =0x7f7f7f7f; - Constll linf = (1ll<< -); + Const DoubleEPS = 1e-8; A Const DoublePie=acos (-1.0); at Const intd1x[]= {0,-1,0,1}; - Const intd1y[]= {-1,0,1,0}; - Const intd2x[]= {0,-1,0,1}; - Const intd2y[]= {1,0,-1,0}; - Const intfx[]= {-1,-1,-1,0,0,1,1,1}; - Const intfy[]= {-1,0,1,-1,1,-1,0,1}; inInlineintMin_32 (int(a),int(b)) {return(a) < (b)?(a):(B); -InlineintMax_32 (int(a),int(b)) {return(a) > (b)?(a):(B); toInlineLong LongMin_64 (Long Long(a),Long Long(b)) {return(a) < (b)?(a):(B); +InlineLong LongMax_64 (Long Long(a),Long Long(b)) {return(a) > (b)?(a):(B); - /***************************************/ the voidOpenFile () { *Freopen ("data.in","RB", stdin); $Freopen ("Data.out","WB", stdout);Panax Notoginseng } - /********************** Gorgeous split line, above for template part *****************/ the  + intdp[ +][20000];//status of the balance on behalf of the I hook A intc[ +]; the intg[ +]; + intMain () - { $     intc,g; $      while(SCANF ("%d%d", &c,&g)! =EOF) -     { -Memset (c,0,sizeof(c)); theMemset (G,0,sizeof(g)); -Memset (DP,0,sizeof(DP));Wuyi         inti,j,k; the          for(i=1; i<=c;i++) -scanf"%d",&c[i]); Wu          for(i=1; i<=g;i++) -scanf"%d",&g[i]); About        //For (i=0;i<=16000;i++) $dp[0][8000]=1;//Initialize -          for(i=1; i<=g;i++) -              for(j=0; j<=16000; j + +) -                  for(k=1; k<=c;k++) A                     if(j>=c[k]*G[i]) +dp[i][j]+=dp[i-1][j-c[k]*G[i]]; theprintf"%d\n", dp[g][8000]); -     } $     return 0; the}

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poj1837 (Balance)