joj1995 Energy

 1995: Energy

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Result	TIME Limit	MEMORY Limit	Run Times	AC Times	JUDGE
	3s	10240K	1366	357	Standard

Mr. Jojer is a very famous chemist. He is doing a research about behavior of a group of atoms. Atoms may have different energy and energy can be positive or negative or zero, e.g. 18 or -9. Absolute value of energy can not be more than 100. Any number of continuous atoms can form an atom-group. Energy of an atom-group is defined by the sum of energy of all the atoms in the group. All the atoms form an atom-community which is a line formed by all the atoms one by one. Energy of an atom-community is defined by the greatest energy of an atom-group that can be formed by atoms in the atom-community. The problem is, given an atom-community, to calculate its energy.

Input

The input contains several test cases. Each test case consists of two lines describing an atom-community. The first line of each test case contains an integer N(N<=1000000), the number of atoms in the atom-community. The second line of each test case contains N integers, separated by spaces, each representing energy of an atom, given in the order according to the atom-community. The last test case marks by N=-1, which you should not proceed.

Output

For each test case(atom-community description), print a single line containing the energy.

Sample Input

5

8 0 6 4 -1

-1

Sample Output

18

 

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DP的经典问题，最大子串和。

 

 1 #include <stdio.h>

 2 

 3 int main()

 4 {

 5     int a[1000005];

 6     int n;

 7     int i;

 8     int maxsum, tmpsum;

 9 

10     while (scanf("%d", &n) == 0, n != -1)

11     {

12         tmpsum = 0;

13         maxsum = -10000;

14         for (i=0; i<n; ++i)

15         {

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

17         }

18 

19         for (i=0; i<n; ++i)

20         {

21             tmpsum += a[i];

22             if (tmpsum > maxsum)

23             {

24                 maxsum = tmpsum;

25             }

26             else if (tmpsum < 0)

27             {

28                 tmpsum = 0;

29             }

30         }

31         printf("%d\n", maxsum);

32     }

33 

34 

35     return 0;

36 }