int main() {
int a[17] = { 13, -3, -25, -20, -3, -16, 23, 18, 20, -7, 12, -5, 22, -15, -4, 7, 0};
int b[9] = {-2, 1, -3, 4, -1, 2, 1, -5, 4};
struct value max;
max = FIND_MAXIMUM_SUBARRAY(a, 0, 16);
printf("%d, %d, %d, %d, %d\n", max.low, max.high, max.sum, a[max.low], a[max.high]);
max = FIND_MAXIMUM_SUBARRAY(b, 0, 8);
printf("%d, %d, %d, %d, %d\n", max.low, max.high, max.sum, b[max.low], b[max.high]);
return 0;
}
RetValue
FIND_MAXIMUM_SUBARRAY(int* A, int low, int high)
{
RetValue ret;
if(high == low) { // 1
ret.max_left = low;
ret.max_right = high;
ret.sum = A[low];
#ifdef DEBUG
printRet(ret);
#endif
return ret; // 2 base case: only one element
} else {
int mid = (low + high) / 2; // 3
#ifdef DEBUG
printf("FIND_MAXIMUM_SUBARRAY(low: %d, mid: %d)\n", low, mid);
#endif
RetValue leftRet = FIND_MAXIMUM_SUBARRAY(A, low, mid); // 4
#ifdef DEBUG
printf("FIND_MAXIMUM_SUBARRAY(mid+1: %d, high: %d)\n", mid+1, high);
#endif
RetValue rightRet = FIND_MAXIMUM_SUBARRAY(A, mid + 1, high); // 5
#ifdef DEBUG
printf("FIND_MAX_CROSSING_SUBARRAY(low: %d, mid: %d, high: %d)\n", low, mid, high);
#endif
RetValue crossRet = FIND_MAX_CROSSING_SUBARRAY(A, low, mid, high); //6
#ifdef DEBUG
printf("leftRet ");printRet(leftRet);
printf("rightRet ");printRet(rightRet);
printf("crossRet ");printRet(crossRet);
#endif
if (leftRet.sum >= rightRet.sum && leftRet.sum >= crossRet.sum){ // 7
#ifdef DEBUG
printf("Choose left\n");
#endif
return leftRet; // 8
} else if (rightRet.sum >= leftRet.sum && rightRet.sum >= crossRet.sum){ // 9
#ifdef DEBUG
printf("Choose right\n");
#endif
return rightRet; // 10
} else {
#ifdef DEBUG
printf("Choose cross\n");
#endif
return crossRet; // 11
}
}
}
int main(void)
{
int A[10]={1,3,6,2,8,-5,-6,7,3,5};
node* n =FIND_MAXIMUM_SUBARRAY(A,0,9);
printf("low:%d high:%d sum:%d\n",n->low,n->high,n->data);
return 0;
}
node* FIND_MAXIMUM_SUBARRAY(int* A,int low , int high)
{
node* n;
n=(node* )malloc(sizeof(node)*1);
if(low==high)
{
//printf("%d",A[0]);
n->data=A[low];
n->high=high;
n->low=low;
return n;
}
int mid=(high+low)/2;
node* left=FIND_MAXIMUM_SUBARRAY(A,low,mid);
node* right=FIND_MAXIMUM_SUBARRAY(A,mid+1,high);
node mide=FIND_MAX_CROSSING_SUBARRAY(A,low ,mid, high);
if(left->data>=right->data)
{
n->data=left->data;
n->high=left->high;
n->low=left->low;
}
else if(right->data>=mide.data)
{
n->data=right->data;
n->high=right->high;
n->low=right->low;
}
else
{
n->data=mide.data;
n->high=mide.high;
n->low=mide.low;
}
return n;
}
