poj2593 Max Sequence

和poj2479同一类型
#include <stdio.h>
#include <string.h>
#define num 100005
int main()
{
  int n,i,sum,maxsum;
  int a[num],arr_1[num],arr_2[num];
  while(scanf("%d",&n)!=EOF&&n)
  {
    memset(a,0,sizeof(a));
    memset(arr_1,0,sizeof(arr_1));
    memset(arr_2,0,sizeof(arr_2));
    sum=0,maxsum=-1005;
    for(i=0;i<n;i++)
    {
        scanf("%d",&a[i]);
        sum+=a[i];
        if(sum>maxsum)
            maxsum=sum;
        if(sum<0)
      sum=0;
        arr_1[i]=maxsum;
      }
      sum=0,maxsum=-1005;
      for(i=n-1;i>=0;i--)
      {
        sum+=a[i];
        if(sum>maxsum)
            maxsum=sum;
        if(sum<0)
            sum=0;
        arr_2[i]=maxsum;
      }
      maxsum=-1005;
      for(i=0;i<n-1;i++)
      if(arr_1[i]+arr_2[i+1]>maxsum)
          maxsum=arr_1[i]+arr_2[i+1];
      printf("%d\n",maxsum);
  }
  return 0;
}