算法导论最大子数组问题

#include"stdio.h"
int findMaxCrossingSubarray(int a[],int low,int high);
int findMaximumSubarray(int a[],int low,int high);
int maxLeft,maxRight;
int main()
{
    int a[100] = {0,13,-3,-25,20,-3,-16,-23,18,20,-7,12,-5,-22,15,-4,7};
    int maxSum;
    maxSum = findMaximumSubarray(a,1,16);
    printf("%d %d\n",maxLeft,maxRight);
    printf("%d\n",maxSum);
    return 0;
}
int findMaxCrossingSubarray(int a[],int low,int high)
{
    int i,j;
    int mid;
    int leftSum = -9999,rightSum = -9999;
    int sum = 0;

    mid = (low + high) / 2;
    for(i = mid;i>=1;i--)
    {
        sum = sum + a[i];
        if(sum > leftSum)
        {
            leftSum = sum;
            maxLeft = i;
        }
    }
    sum = 0;
    for(j = mid +1;j<=high;j++)
    {
        sum = sum + a[j];
        if(sum > rightSum)
        {
            rightSum = sum;
            maxRight = j;
        }
    }
    return leftSum + rightSum;
}
int findMaximumSubarray(int a[],int low,int high)
{
    int mid;
    int leftSum,crossSum,rightSum;
    if(high == low)
        return a[low];
    else
    {
        mid = (low + high) / 2;
        leftSum = findMaximumSubarray(a,low,mid);
        rightSum = findMaximumSubarray(a,mid + 1,high);
        crossSum = findMaxCrossingSubarray(a,low,high);
        if(leftSum >= rightSum && leftSum >= crossSum)
            return leftSum;
        else if(rightSum >= leftSum && rightSum >= crossSum)
            return rightSum;
        else
            return crossSum;
    }
}