hdu 1024 Max Sum Plus Plus

http://acm.hdu.edu.cn/showproblem.php?pid=1024

状态转移方程： dp[j]=max(dp[j-1]+a[j],pre[j-1]+a[j]);

 1 #include <cstdio>

 2 #include <cstring>

 3 #include <algorithm>

 4 #define maxn 1000010

 5 #define ll int

 6 using namespace std;

 7 const int inf=1<<29;

 8 

 9 ll dp[maxn],pre[maxn];

10 int a[maxn];

11 int n,m;

12 ll max2;

13 

14 ll max1(ll a,ll b)

15 {

16     if(a>b) return a;

17     return b;

18 }

19 

20 int main()

21 {

22     while(scanf("%d%d",&m,&n)!=EOF)

23     {

24         for(int i=1; i<=n; i++)

25         {

26             scanf("%d",&a[i]);

27         }

28         memset(dp,0,sizeof(dp));

29         memset(pre,0,sizeof(pre));

30         for(int i=1; i<=m; i++)

31         {

32             max2=-inf;

33             for(int j=i; j<=n; j++)

34             {

35                 dp[j]=max(dp[j-1]+a[j],pre[j-1]+a[j]);

36                 pre[j-1]=max2;

37                 max2=max(max2,dp[j]);

38             }

39         }

40         printf("%d\n",max2);

41     }

42     return 0;

43 }

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