# Find the position of box which occupies the given ball in Python

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Suppose we have two arrays A and B. The size of A is the number of rows and A[i] is the number of boxes in the ith row. And B is the array of balls where B[i] denotes a number on the ball. Given that ball i (value B[i]) will be placed in a box whose position from starting is B[i]. We have to find the row and column of the boxes corresponding to each B[i].

So, if the input is like A = [3, 4, 5, 6], B = [1, 3, 5, 2], then the output will be [(1, 1), (1, 3), (2, 2), (1, 2)] as B[0] = 1, then the box position will be 1st row, 1st column B[1] = 3, then the box position will be 1st row, 3rd column, B[2] = 5, then the box position will be 2nd row, 2nd column, B[3] = 2, then the box position will be 1st row, 2nd column

To solve this, we will follow these steps −

• len_a := size of A

• len_b := size of B

• for i in range 1 to len_a, do

• A[i] := A[i] + A[i - 1]

• for i in range 0 to len_b, do

• row := an index where we can insert B[i] to maintain A sorted

• if row >= 1, then

• box_num := B[i] - A[row - 1]

• otherwise,

• box_num := B[i]

• display a pair (row + 1, box_num)

## Example

Let us see the following implementation to get better understanding −

Live Demo

import bisect
def get_position(A, B):
len_a = len(A)
len_b = len(B)
for i in range(1, len_a):
A[i] += A[i - 1]
for i in range(len_b):
row = bisect.bisect_left(A, B[i])
if row >= 1:
box_num = B[i] - A[row - 1]
else:
box_num = B[i]
print ((row + 1, box_num))
A = [3, 4, 5, 6]
B = [1, 3, 5, 2]
get_position(A, B)

## Input

[3, 4, 5, 6], [1, 3, 5, 2]

## Output

(1, 1)
(1, 3)
(2, 2)
(1, 2)
Updated on 27-Aug-2020 06:34:42