分治法之最大子数组问题

自己敲出来的，先把代码贴上来，晚上有时间再写总结

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

};
int a[N];
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;
}