static int MaxSubSum(const int a[],int Left,int Right)
{
    int MaxLeftSum,MaxRightSum;
    int MaxLeftBorderSum,MaxRightBorderSum;
    int Center;
    if(Left==Right)
        if(a[Left]>0)
            return a[Left];
        else
            return 0;
         
    Center=(Left+Right)/2;
    MaxLeftSum =MaxSubSum(a,Left,Center);   //第一句
    MaxRightSum=MaxSubSum(a,Center+1,Right);//第二句
         
    MaxLeftBorderSum=0;LeftBorderSum=0;
    for(i=Center;i>=Left;i--)
    {
        LeftBorderSum+=a[i];
        if(LeftBorderSum>MaxLeftBorderSum)
            MaxLeftBorderSum=LeftBorderSum;
    }
         
    MaxRightBorderSum=0;RightBorderSum=0;
    for(i=Center+1;i<=Right;i++)
    {
        RightBorderSum+=a[i];
        if(RightBorderSum>MaxRightBorderSum)
            MaxRightBorderSum=RightBorderSum;
    }
    return Max3(MaxLeftSum,MaxRightSum,MaxLeftBorderSum+MaxRightBorderSum);
}
 
int MaxSubsequenceSum(const int a[], int n)
{
    return MaxSubSum(a,o,n-1);
}