左式堆decreaseKey

《数据结构与算法分析——c语言描述》 练习6.20 答案

先删除再插入

static swapLeftRightSon(PriorityQueue h) {
	PriorityQueue temp;
	temp = h->right;
	h->right = h->left;
	h->left = temp;
}


static PriorityQueue deleteKey_internal(ElementType X, ElementType delta, int *isFind, PriorityQueue h) {
	if (h) {
		if (X > h->element) {
			h->left = deleteKey_internal(X, delta, isFind, h->left);
			if (*isFind == 0) {//没有找到
				h->right = deleteKey_internal(X, delta, isFind, h->right);
			}
			if (h->left == NULL) {
				h->left = h->right;
				h->right = NULL;
				h->np1 = 0;
			}
			else if (h->right == NULL) {
				h->np1 = 0;
			}
			else {
				if (h->right->np1 > h->left->np1)
					swapLeftRightSon(h);
				h->np1 = h->right->np1 + 1;
			}
		}
		else if (X == h->element) {
			PriorityQueue newMergeRoot = merge(h->left, h->right);
			free(h);
			*isFind = 1;
			h = newMergeRoot;
		}
	}
	return h;
}


PriorityQueue decreaseKey(ElementType X, ElementType delta, PriorityQueue h) {
	int isFind = 0;
	h = deleteKey_internal(X, delta, &isFind, h);
	insert(X - delta, h);
	return h;
}