Array-1

Problem 1

Given an array nums of n integers where n > 1, return an array output such that output[i] is equal to the product of all the elements of nums except nums[i].

Example:

Input: [1,2,3,4] Output: [24,12,8,6] Note: Please solve it without division and in O(n).

Follow up: Could you solve it with constant space complexity? (The output array does not count as extra space for the purpose of space complexity analysis.)

At any given element we need the product of elements to the left of the element and right of the

element.

Create a result array by taking product of the left elements except the number itself.

On this result array now we will take product of the right elements except the number itself.

The resultant array will return us the products.

Problem 2

Given a matrix of M x N elements (M rows, N columns), return all elements of the matrix in diagonal order as shown in the below image.

Example:

Input:

[

[ 1, 2, 3 ],

[ 4, 5, 6 ],

[ 7, 8, 9 ]

]

Output: [1,2,4,7,5,3,6,8,9]

Get the number of rows and columns and initialize a result array of size product of rows & columns

to store the result.

Initialize an index as '0' and start parsing the matrix by appending the first element

First we go in the upward direction, by incrementing the row index and change the direction to False

until we reach the roof condition of the matrix

Second we go down once the roof is reached and collect all the column index elements and change

direction to True until we hit the bottom row of the matrix. The condition 'True' indicates to go UP.

Return the result array.

Problem 3

Given a matrix of m x n elements (m rows, n columns), return all elements of the matrix in spiral order.

Example 1:

Input:

[

[ 1, 2, 3 ],

[ 4, 5, 6 ],

[ 7, 8, 9 ]

] Output: [1,2,3,6,9,8,7,4,5] Example 2:

Input:

[

[1, 2, 3, 4],

[5, 6, 7, 8],

[9,10,11,12]

] Output: [1,2,3,4,8,12,11,10,9,5,6,7]

Initialize an array of size that is rows times columns

First we move from left to right on the top row, by parsing on each column and same row, collect

all elements

Move from top to bottom by parsing each row and same column, collect all elements

Move from right to left but check the condition top <= bottom so that we don't collect

duplicates, collect all elements

Move from bottom to top but check the condition that left <= right to make sure we don't collect

duplicates. Parse each row element and same column, collect all elements.