# Binary Search doubt

mukki pandey

Ranch Hand

Posts: 58

posted 7 years ago

Given a properly prepared String array containing five elements, which

range of results could a

proper invocation of Arrays.binarySearch() produce?

A. 0 through 4

B. 0 through 5

C. -1 through 4

D. -1 through 5

E. -5 through 4

F. -5 through 5

G. -6 through 4

H. -6 through 5

Answer:

3 G is correct. If a match is found, binarySearch()will return the

index of the element that was matched. If no match is found, binarySearch() will return a negative number that,if inverted and then decremented, gives you the insertion point (array index) at which the

value searched on should be inserted into the array to maintain a

proper sort.

A, B, C, D, E, F, and H are incorrect based on the above. (Objective

6.5)

Can any one please expalin me why only G

Source KB Book

range of results could a

proper invocation of Arrays.binarySearch() produce?

A. 0 through 4

B. 0 through 5

C. -1 through 4

D. -1 through 5

E. -5 through 4

F. -5 through 5

G. -6 through 4

H. -6 through 5

Answer:

3 G is correct. If a match is found, binarySearch()will return the

index of the element that was matched. If no match is found, binarySearch() will return a negative number that,if inverted and then decremented, gives you the insertion point (array index) at which the

value searched on should be inserted into the array to maintain a

proper sort.

A, B, C, D, E, F, and H are incorrect based on the above. (Objective

6.5)

Can any one please expalin me why only G

Source KB Book

Jeevitesh Singh

Greenhorn

Posts: 28

posted 7 years ago

hi friend.....

you must be knowing if it gets a match it returns the index......

therefore you must be understanding 0 to 4.......

for the ans of -6 to -1 is

that index returned for no match is

as (-(insertion point)-1)....we have insertion points as .....

0,1,2,3,4,5......

5 because we can insert it after the last element......

putting these in the formula you will have -1 to -6.....

you must be knowing if it gets a match it returns the index......

therefore you must be understanding 0 to 4.......

for the ans of -6 to -1 is

that index returned for no match is

as (-(insertion point)-1)....we have insertion points as .....

0,1,2,3,4,5......

5 because we can insert it after the last element......

putting these in the formula you will have -1 to -6.....

posted 7 years ago

The API says a binary search returns the...

So for a sorted array containing 5 elements...

...index of the search key, if it is contained in the array; otherwise, (-(insertion point) - 1). The insertion point is defined as the point at which the key would be inserted into the array: the index of the first element greater than the key, or a.length if all elements in the array are less than the specified key.

So for a sorted array containing 5 elements...

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