Question

Given a circular array implemented in Python: blockCapacity=100, dataStartIndex=80, dataCount=87. Figure out the index of the last data item?

Answer 1

Solution:

The circular array will again start from index 0 when then block size is full.

Given:

Circular array

BlockCapacity = 100
dataStartIndex = 80
dataCount = 87

Answer:

The index of last element is 66

Explanation:

In a circular array of size 100 the index ranges from 0 - 99

Here the data startIndex is 80 while the count is 87

The first 20 elements will be in index 80 - 99.
The remaining number of elements are 87-20 = 67

These 67 elements will be in indexes 0-66.

So we can conclude the index of last data item is 66

Index and data element numbers:

index	80	81	82	83	84	85	86	87	88	89
data element	1	2	3	4	5	6	7	8	9	10
index	90	91	92	93	94	95	96	97	98	99
data element	11	12	13	14	15	16	17	18	19	20
index	0	1	2	3	4	5	6	7	8	9
data element	21	22	23	24	25	26	27	28	29	30
index	10	11	12	13	14	15	16	17	18	19
data element	31	32	33	34	35	36	37	38	39	40
index	20	21	22	23	24	25	26	27	28	29
data element	41	42	43	44	45	46	47	48	49	50
index	30	31	32	33	34	35	36	37	38	39
data element	51	52	53	54	55	56	57	58	59	60
index	40	41	42	43	44	45	46	47	48	49
data element	61	62	63	64	65	66	67	68	69	70
index	50	51	52	53	54	55	56	57	58	59
data element	71	72	73	74	75	76	77	78	79	80
index	60	61	62	63	64	65	66
data element	81	82	83	84	85	86	87