Problem:
Maximum Sum Sequence

Given a sequence of numbers a1, a2, a3, ..., an, find the maximum sum of a contiguous subsequence of those numbers. Note that, a subsequence of one element is also a contiquous subsequence.

Input

The input consists of multiple datasets. Each data set consists of:

n
a1
a2
.
.
an

You can assume that 1 ≤ n ≤ 5000 and -100000 ≤ ai ≤ 100000.

The input end with a line consisting of a single 0.

Output

For each dataset, print the maximum sum in a line.

Sample Input

7
-5
-1
6
4
9
-6
-7
13
1
2
3
2
-2
-1
1
2
3
2
1
-2
1
3
1000
-200
201
0

Output for the Sample Input

19
14
1001

Solution in C (judge verdict: Wrong Answer)

#include <stdio.h>

int main(){
  long data, sum, max;
  int i, j, k;
  int num, nnum;
  long setdata[5000];
  int isPos;

  while(1){
    scanf("%d", &num);
    if(num==0) break;
    isPos=1; nnum=0; sum=0;
    setdata[0]=0;
    for(i=0; i<num; i++){
      scanf("%ld", &data);
      if(data==0) continue;
      if(data>0 && isPos==0){
        setdata[nnum]=sum;
        sum=data;
        nnum++; isPos=1;
      }
      else if(data<0 && isPos==1){
        setdata[nnum]=sum;
        sum=data;
        nnum++; isPos=0;
      }
      else {
        sum+=data;
      }
    }
    if(sum!=0){
      setdata[nnum]=sum;
      nnum++;
    }
    max=0;
    for(i=0; i<nnum; i++){
      for(j=i; j<nnum; j++){
        sum=0;
        for(k=i; k<=j; k++){
          sum+=setdata[k];
        }
        if(max<sum) max=sum;
      }
    }
  printf("%ld\n", max);
  }

  return 0;
}