ZOJ2059 The Twin Towers，DP

/*******************************************************************************
* Author : Neo Fung
* Email : neosfung@gmail.com
* Last modified : 2011-07-17 19:59
* Filename : ZOJ2059 The Twin Towers.cpp
* Description : http://acm.zju.edu.cn/onlinejudge/showProblem.do?problemCode=2059 * *****************************************************************************/
// ZOJ2059 The Twin Towers.cpp : Defines the entry point for the console application.
//
// #include "stdafx.h"
// #define DEBUG

#include <fstream>
#include <stdio.h>
#include <iostream>
#include <string.h>
#include <math.h>
#include <algorithm>
#include <numeric>
#include <functional>
#include <memory.h>
#define MAX 2010
using namespace std;

int main(void)
{
#ifdef DEBUG
freopen("C:/Users/neo/Desktop/stdin.txt","r",stdin);
freopen("C:/Users/neo/Desktop/stdout.txt","w",stdout);
#endif
int n,dp[MAX],pre[MAX];
int x;

while(scanf("%d",&n))
{
if(n<0)
break;
memset(dp,-1,sizeof(dp));
memset(pre,-1,sizeof(pre));
dp[0]=0;
pre[0]=0;
int sum=0;
while(n--)
{
scanf("%d",&x);
for(int i=0;i<=sum;++i)
{
if(pre[i]>=0)
{
//加在较高的塔上
if(i+x<=MAX)
dp[i+x]=max(pre[i+x],pre[i]);
//加在较低的塔上，较低的塔仍然比较高的塔低
if(x<i)
dp[i-x]=max(pre[i]+x,dp[i-x]);
else
dp[x-i]=max(pre[i]+i,dp[x-i]);  //加在较低的塔上，变得比较高的塔高
}
}
sum+=x;
memcpy(pre,dp,sizeof(dp));
}
if(pre[0])
printf("%d\n",pre[0]);
else
printf("Sorry\n");
}
return 0;
}