Update Permutation and Combination cheatsheets. (trekhleb#963)

Author: trekhleb

src/algorithms/sets/combinations/README.md

@@ -5,14 +5,14 @@ When the order doesn't matter, it is a **Combination**.
 When the order **does** matter it is a **Permutation**.
 
 **"My fruit salad is a combination of apples, grapes and bananas"**
-We don't care what order the fruits are in, they could also be 
-"bananas, grapes and apples" or "grapes, apples and bananas", 
+We don't care what order the fruits are in, they could also be
+"bananas, grapes and apples" or "grapes, apples and bananas",
 its the same fruit salad.
 
 ## Combinations without repetitions
 
-This is how lotteries work. The numbers are drawn one at a 
-time, and if we have the lucky numbers (no matter what order) 
+This is how lotteries work. The numbers are drawn one at a
+time, and if we have the lucky numbers (no matter what order)
 we win!
 
 No Repetition: such as lottery numbers `(2,14,15,27,30,33)`
@@ -30,12 +30,12 @@ It is often called "n choose r" (such as "16 choose 3"). And is also known as th
 
 Repetition is Allowed: such as coins in your pocket `(5,5,5,10,10)`
 
-Or let us say there are five flavours of ice cream: 
+Or let us say there are five flavours of ice cream:
 `banana`, `chocolate`, `lemon`, `strawberry` and `vanilla`.
 
 We can have three scoops. How many variations will there be?
 
-Let's use letters for the flavours: `{b, c, l, s, v}`. 
+Let's use letters for the flavours: `{b, c, l, s, v}`.
 Example selections include:
 
 - `{c, c, c}` (3 scoops of chocolate)
@@ -46,23 +46,21 @@ Example selections include:
 
 ![Formula](https://www.mathsisfun.com/combinatorics/images/combinations-repeat.gif)
 
-Where `n` is the number of things to choose from, and we 
-choose `r` of them. Repetition allowed, 
+Where `n` is the number of things to choose from, and we
+choose `r` of them. Repetition allowed,
 order doesn't matter.
 
-## Cheat Sheets
+## Cheatsheet
 
-Permutations cheat sheet
+![Permutations and Combinations Overview](./images/overview.png)
 
-![Permutations Cheat Sheet](https://cdn-images-1.medium.com/max/2000/1*JNK-n0Pt0Vbxk0lxVpgT5A.png)
+![Combinations overview](./images/combinations-overview.jpg)
 
-Combinations cheat sheet
+| | |
+| --- | --- |
+|![Combinations with repetition](./images/combinations-with-repetitions.jpg) | ![Combinations without repetition](./images/combinations-without-repetitions.jpg) |
 
-![Combinations Cheat Sheet](https://cdn-images-1.medium.com/max/2000/1*7cFRn8jW4g_91YgDAbmxRQ.png)
-
-Permutations/combinations algorithm ideas.
-
-![Algorithms Idea](https://cdn-images-1.medium.com/max/2000/1*vLsSsZMnesCFPCYTYMbxrQ.png)
+*Made with [okso.app](https://okso.app)*
 
 ## References
 

src/algorithms/sets/combinations/images/combinations-overview.jpg

@@ -4,13 +4,13 @@ When the order doesn't matter, it is a **Combination**.
 
 When the order **does** matter it is a **Permutation**.
 
-**"The combination to the safe is 472"**. We do care about the order. `724` won't work, nor will `247`. 
+**"The combination to the safe is 472"**. We do care about the order. `724` won't work, nor will `247`.
 It has to be exactly `4-7-2`.
 
 ## Permutations without repetitions
 
-A permutation, also called an “arrangement number” or “order”, is a rearrangement of 
-the elements of an ordered list `S` into a one-to-one correspondence with `S` itself. 
+A permutation, also called an “arrangement number” or “order”, is a rearrangement of
+the elements of an ordered list `S` into a one-to-one correspondence with `S` itself.
 
 Below are the permutations of string `ABC`.
 
@@ -37,19 +37,17 @@ For example the the lock below: it could be `333`.
 n * n * n ... (r times) = n^r
 ```
 
-## Cheat Sheets
+## Cheatsheet
 
-Permutations cheat sheet
+![Permutations and Combinations Overview](./images/overview.png)
 
-![Permutations Cheat Sheet](https://cdn-images-1.medium.com/max/2000/1*JNK-n0Pt0Vbxk0lxVpgT5A.png)
+![Permutations overview](./images/permutations-overview.jpeg)
 
-Combinations cheat sheet
+| | |
+| --- | --- |
+|![Permutations with repetition](./images/permutations-with-repetitions.jpg) | ![Permutations without repetition](./images/permutations-without-repetitions.jpg) |
 
-![Combinations Cheat Sheet](https://cdn-images-1.medium.com/max/2000/1*7cFRn8jW4g_91YgDAbmxRQ.png)
-
-Permutations/combinations algorithm ideas.
-
-![Algorithms Idea](https://cdn-images-1.medium.com/max/2000/1*vLsSsZMnesCFPCYTYMbxrQ.png)
+*Made with [okso.app](https://okso.app)*
 
 ## References