分治法之最大子数组问题

#include<stdio.h>
#define N 10
struct Max{
int low;
int high;
int sum;

};
int a
;
Max Findcrossing(int* a,int low,int middle,int high);
Max FindSub(int* a,int low,int high);
int main()
{
Max m;
int i;
for(i=0;i<N;i++)
scanf("%d",&a[i]);
m=FindSub(a,0,9);
printf("%d\n%d\n%d",m.sum,m.low,m.high);

return 0;
}
Max FindSub(int* a,int low,int high)
{
Max max_sub;
Max max_left;
Max max_right;
Max max_cross;

if(high==low)
{
max_sub.high=high;
max_sub.low=low;
max_sub.sum=a[low];
}
else
{
int middle=(low+high)/2;

max_left=FindSub(a,low,middle);
max_right=FindSub(a,middle+1,high);
max_cross=Findcrossing(a,low,middle,high);
if(max_left.sum>=max_right.sum&&max_left.sum>=max_cross.sum)
{
max_sub.high=max_left.high;
max_sub.low=max_left.low;
max_sub.sum=max_left.sum;
}
else if(max_right.sum>=max_left.sum&&max_right.sum>=max_cross.sum)
{
max_sub.high=max_right.high;
max_sub.low=max_right.low;
max_sub.sum=max_right.sum;
}
else
{
max_sub.high=max_cross.high;
max_sub.low=max_cross.low;
max_sub.sum=max_cross.sum;
}

}

return max_sub;
}
Max Findcrossing(int* a,int low,int middle,int high)
{
int i,j;
Max max_cross;

int left_i,sum_left=0,MAX_left=-10000;
for(i=middle;i>=low;i--)
{
sum_left+=a[i];
if(sum_left>MAX_left)
{
MAX_left=sum_left;
left_i=i;
}
}
int right_j,sum_right=0,MAX_right=-10000;
for(j=middle+1;j<=high;j++)
{
sum_right+=a[j];
if(sum_right>MAX_right)
{
MAX_right=sum_right;
right_j=j;
}

}
max_cross.sum=MAX_left+MAX_right;
max_cross.low=left_i;
max_cross.high=right_j;
return max_cross;
}