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。

 

#include <stdio.h>

int main()
{
    int a[1000005];
    int n;
    int i;
    int maxsum, tmpsum;

    while (scanf("%d", &n) == 0, n != -1)
    {
        tmpsum = 0;
        maxsum = -10000;
        for (i=0; i<n; ++i)
        {
            scanf("%d", &a[i]);
        }

        for (i=0; i<n; ++i)
        {
            tmpsum += a[i];
            if (tmpsum > maxsum)
            {
                maxsum = tmpsum;
            }
            else if (tmpsum < 0)
            {
                tmpsum = 0;
            }
        }
        printf("%d\n", maxsum);
    }


    return 0;
}