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HDU 2845（dp）
题目链接：http://acm.hdu.edu.cn/showproblem.php?pid=2845
Beans
Time Limit: 2000/1000 MS (Java/Others) Memory Limit: 32768/32768 K (Java/Others)
Total Submission(s): 3097 Accepted Submission(s): 1495
Problem Description
Bean-eating is an interesting game, everyone owns an M*N matrix, which is filled with different qualities beans. Meantime, there is only one bean in any 1*1 grid. Now you want to eat the beans and collect the qualities, but everyone must obey by the following rules: if you eat the bean at the coordinate(x, y), you can’t eat the beans anyway at the coordinates listed (if exiting): (x, y-1), (x, y+1), and the both rows whose abscissas are x-1 and x+1.
Now, how much qualities can you eat and then get ?
Now, how much qualities can you eat and then get ?
Input
There are a few cases. In each case, there are two integer M (row number) and N (column number). The next M lines each contain N integers, representing the qualities of the beans. We can make sure that the quality of bean isn‘t beyond 1000, and 1<=M*N<=200000.
Output
For each case, you just output the MAX qualities you can eat and then get.
Sample Input
4 611 0 7 5 13 978 4 81 6 22 41 40 9 34 16 1011 22 0 33 39 6
Sample Output
242
题意：按照规则取出的数字和最大。规则：取了坐标为（x,y）的数字就不能再取坐标为（x,y-1）、（x,y+1）、（x-1,*）和（x+1,*）的数字，*表示任意位置。
分析：首先找出每一行每个位置和最佳情况；每个数字可取可不取，即：dpx[i] = max(dpx[i-1], dpx[i-2] + 该行第 i 个数字)。然后再找列的和最佳情况，此时只有一列，即每一行的最大值组成的列，则：dyp[i] = max(dpy[i-1], dpy[i-2] + 第 i 行的最大值)。
1 #include <cstdio> 2 #include <cmath> 3 #include <iostream> 4 using namespace std; 5 6 int n,m,s; 7 int dpx[222222],dpy[222222]; 8 9 int main ()10 {11 int i,j,k;12 while (scanf ("%d%d",&n,&m)==2)13 {14 memset(dpx, 0, sizeof(dpx));15 memset(dpy, 0, sizeof(dpy));//先对两个数组清零16 for (i=2; i<=n+1; i++)17 {18 for (j=2; j<=m+1; j++)19 {20 scanf ("%d",&s);21 dpx[j] = max(dpx[j-1], dpx[j-2] + s);//每个状态的值等于之前的某个状态加上另一个状态22 }23 dpy[i] = max(dpy[i-1], dpy[i-2] + dpx[m+1]);//因为只有加法，dpx[m+1]为每一行的最大值24 }25 printf ("%d\n",dpy[n+1]);26 }27 return 0;28 }
HDU 2845（dp）
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