https://github.com/amrhossamdev/matrix-flatten
A 3D matrix is to be stored in a 1D vector (flattened).
https://github.com/amrhossamdev/matrix-flatten
Last synced: 10 months ago
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A 3D matrix is to be stored in a 1D vector (flattened).
- Host: GitHub
- URL: https://github.com/amrhossamdev/matrix-flatten
- Owner: amrhossamdev
- Created: 2022-05-19T03:50:36.000Z (over 3 years ago)
- Default Branch: main
- Last Pushed: 2022-05-20T03:58:17.000Z (over 3 years ago)
- Last Synced: 2025-01-22T10:44:31.639Z (12 months ago)
- Language: C++
- Homepage:
- Size: 97.7 KB
- Stars: 0
- Watchers: 1
- Forks: 0
- Open Issues: 0
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Metadata Files:
- Readme: README.md
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README
# Problem Description
1. A 3D matrix is to be stored in a 1D vector (flattened)
2. The 3D matrix is of size n x m x p and is indexed by i, j, k
3. The 1D vector is of size q and is indexed by y
# Requirements
Implement the following functions:
1. Create a 1D vector suitable for storing the 3D matrix
2. Convert the 3D matrix index (i, j, k) to a suitable 1D vector index (y). Must be O(1)
# Solution
3d array is just an array of `2d arrays`, to convert 2d array to 1d array, we calculte 2d array idx = weight*rowI + colJ
but what we will do in the 3d array case ?
Solution is pretty simple all we need is to know to total indecies or the first index in my 2d array for example :
we need to calculte indecies for that 2d array !
1. First we need to know the last previous index it will be equal to = `7` then we will increment it by 1 to get first index in the 2d array i'm in !
2. we need to calculte the index `for pos [2,1,0]` so i know my `previous index was 7` and `my first 2d array index is 8`
3. so the answer will be `8 + [current 2d array idx] = w*rowJ + colI = 2*1 + 0 == 8 + 2 == 10 !`
# Used algorithm
1. `2d array idx = width * row + col`
2. `3d array idx = (width * height * i) + [2d array idx]`
finally -> `int idx = (m * p * i) + (m * j) + k;`
# Example
