POJ 1036 Gansters (DP)

题意：有个伸缩门，门的宽度0~K，每个时间可以伸长或缩短1个单位，有N个流氓，他们在T时刻到达，如果这时门的宽度正好与他们的stoutness相等时，便可获得一定的收入，问最大的收入是多少。

思路：典型的动态规划，用dp[t][k]来记录t时刻门宽度为k时的最大收入，由于这个值只与dp[t-1][]有关，所以可用滚动数组来实现，不然会超内存，另外存储流氓时还是利用struct来存放，否则内存不够，还有就是初始化的问题了：在t时刻(t<k)门的宽度是不可能大于t的，需要注意。

 

#include <iostream>
#include <cstdio>
#include <algorithm>
#include <memory.h>
#include <cmath>
#include <bitset>
#include <vector>
using namespace std;

const int BORDER = (1<<26)-1;
const int MAXSIZE = 37;
const int MAXN = 110;
const int INF = 0x6ffffff;
#define CLR(x,y) memset(x,y,sizeof(x))
#define ADD(x) x=((x+1)&BORDER)
#define IN(x) scanf("%d",&x)
#define OUT(x) printf("%d\n",x)
#define MIN(m,v) (m)<(v)?(m):(v)
#define MAX(m,v) (m)>(v)?(m):(v)
#define ABS(x) (x>0?x:-x)

typedef struct{
    int stout,pros;
    int next;
}Edge;
Edge edge[MAXN];
int pros[MAXN],dp[2][30005],come[MAXN],stout[MAXN];
int net[30005];
int con,N,T,K,index;
void add_edge(const int& u,const int& st,const int& pr)
{
    edge[index].stout = st;
    edge[index].pros = pr;
    edge[index].next = net[u];
    net[u] = index;
    ++index;
}
int get_pros(const int& tim,const int& stout)
{
    int sum = 0;
    for(int i = net[tim]; i != -1; i = edge[i].next)
        if(edge[i].stout == stout)
            sum += edge[i].pros;
    return sum;
}
int init()
{
    con = 0;
    index = 0;
    CLR(net,-1);
    CLR(dp,0);
    return 0;
}
int input()
{
    int i,j,tmp;
    for(i = 0; i < N; ++i)
        IN(come[i]);
    for(i = 0; i < N; ++i)
        IN(pros[i]);
    for(i = 0; i < N; ++i)
        IN(stout[i]);
    for(i = 0; i < N; ++i)
        add_edge(come[i],stout[i],pros[i]);
    return 0;
}
int _dp()
{
    int i,j,tmp,n_door;
    for(i = 1; i <= T; ++i)
    {
        n_door = MIN(i,K);
        dp[con][0] = MAX(dp[1-con][0],dp[1-con][1]);
        dp[con][n_door] = MAX(dp[1-con][n_door],dp[1-con][n_door-1]);
        dp[con][n_door] += get_pros(i,n_door);;
        for(j = 1; j < n_door; ++j)
        {
            tmp = MAX(dp[1-con][j-1],dp[1-con][j]);
            dp[con][j] = MAX(tmp,dp[1-con][j+1]);
            tmp = 0;
            dp[con][j] += get_pros(i,j);
        }
        memcpy(dp[1-con],dp[con],sizeof(come));
        con = 1 - con;
    }
    return 0;
}
int work()
{
    int i,j,tmp;
    _dp();
    tmp = 0;
    for(i = 0; i <= K; ++i)
        tmp = MAX(tmp,dp[con][i]);
    OUT(tmp);
    return 0;
}
int main()
{
    while(scanf("%d%d%d",&N,&K,&T)!=EOF)
    {
        init();
        input();
        work();
    }
    return 0;
}