## Interview Question

Software Engineer / Developers**Country:**United States

I am able to solve the puzzle and answer is

3 2 10

4 0 6

5 12 1

Not clear on how to make it work programmatically ? Will it applicable to all the inputs?

The below points will helpful in writing program

1) Finding LCM of the given numbers to find the multiple of all sides.

2) Deciding on 2 diagonal corner numbers and deciding the other two diagonals

3) Adjusting the remaining 4 numbers in the middle places.

Your puzzle solution doesn't satisfy the following constraint:

"The sum of the east side is 3 more than the sum of the North Side"

3 + 2 + 10 = 15

10 + 6 + 1 = 17

Hey, I already figured out the solution. It is,

```
5 4 3
12 2
1 6 10
```

I need to figure out a way to solve this programatically.

I assumed Directions as like below and it met the rules.

E

3 2 10

N 4 0 6 S

5 12 1

W

Have I assumed the directions in a wrong way?

Logic:

-Take 4 elements from given array for all combination out of 8 elements and assume these 4 elements are the 4 corner of 3X3 mattrix

[4 picked elements will represent in 2D mattrix as follows:]

[a[0][0] , a[0][2], a[2][0], a[2][2]]

-Now take rest of the 4 elements from array and check all the combination so that multiplication of all the phases will be equal

[rest of 4 elements will checked for below mentioned position]

[a[0][1], a[1][0], a[2][1], a[1][2]]

-Now we got 4 phases with equal multiplication

a[0][0] * a[0][1] * a[0][2] ==

a[2][0] * a[2][1] * a[2][2] ==

a[0][0] * a[1][0] * a[2][0] ==

a[2][0] * a[2][1] * a[2][2] ==

-Now find the minimum sum phase and rotate mattrix in any direction until we get minimum sum phase at desired position

-And then we can perform left phase to right phase exchange or top phase to bottom phase exchange to get desired mattrix

exploring all permutations was easier for this. I wrote this in python and using the numpy library:

```
import numpy as np
class matrixPuzzle:
def __init__(self, arr):
self.arr = arr
self.matrix = np.zeros(shape=(3,3))
self.setTotal = set(x for x in arr)
self.setA = set()
self.setB = set()
self.Combs = ()
self.Perms = ()
self.solSet = []
def productValidate(self):
prodArr = [1] * 4 # preserve the products for R0, R2, C0, C2
setProd = set()
for i in xrange(3):
prodArr[0] *= self.matrix[0][i] #R0
prodArr[1] *= self.matrix[2][i] #R2
prodArr[2] *= self.matrix[i][0] #C0
prodArr[3] *= self.matrix[i][2] #C2
setProd = set(x for x in prodArr)
if len(setProd) == 1:
#print 'setProd=', setProd
return 1
else:
return 0
def sumValidate(self):
sumArr = [0] * 4
for i in xrange(3):
sumArr[0] += self.matrix[0][i] #R0 (North)
sumArr[1] += self.matrix[2][i] #R2 (South)
sumArr[2] += self.matrix[i][0] #C0 (West)
sumArr[3] += self.matrix[i][2] #C2 (East)
#Condition to satisfy: W - S = 1 # S - E = 2 # E - N = 3
if (sumArr[2] - sumArr[1] == 1) and (sumArr[1] - sumArr[3] == 2) and (sumArr[3] - sumArr[0] == 3):
return 1
else:
return 0
def findPerms(self, arr):
import itertools as it
#print('permutations')
P = it.permutations(arr, 4)
permPool = tuple(P)
return permPool
def solver(self):
self.Perms = self.findPerms(self.arr)
print 'len of perms:', len(self.Perms)
for tup in self.Perms:
#arrange the corner elements from each tuple in the Permutation
self.matrix[0][0] = tup[0]
self.matrix[0][2] = tup[1]
self.matrix[2][0] = tup[2]
self.matrix[2][2] = tup[3]
# run permutations of the other remaining array elements and fill up the matrix remaining positions
self.setA = set(x for x in tup)
self.setB = self.setTotal - self.setA
permPool = self.findPerms(self.setB)
for tupP in permPool:
self.matrix[0][1] = tupP[0]
self.matrix[2][1] = tupP[1]
self.matrix[1][0] = tupP[2]
self.matrix[1][2] = tupP[3]
#Now validate each matrix
retProd = self.productValidate()
if retProd == 1:
retSum = self.sumValidate()
if retSum == 1:
print 'product valid and sum valid:'
print self.matrix
# Capture the result which satisfies both conditions
self.solSet.append(self.matrix)
if __name__ == '__main__':
arr = [1,2,3,4,5,6,10,12]
mP = matrixPuzzle(arr)
mP.solver()
```

RG, the original poster, please create a new thread for each study problem you need help with. Don't click "edit" on your previous study threads and put a new question in there.

- Kenneth March 20, 2014Thanks!