Create README.md

Author: abhisheks008

Dynamic Programming/Subset Sum Problem/README.md

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+# Subset Sum Problem using Dynamic Programming
+Language used : **Python 3**
+
+## 🎯 Aim
+The aim of this script is to find out if there is a subset of the given set with sum equal to given sum.
+
+## 👉 Purpose
+The main purpose of this script is to show the implementation of Dynamic Programming to find out if there is a subset of the given set with sum equal to given sum.
+
+## 📄 Description
+Given a set of non-negative integers, and a value sum, determine if there is a subset of the given set with sum equal to given sum. 
+```
+Example: 
+
+Input: set[] = {3, 34, 4, 12, 5, 2}, sum = 9
+Output: True  
+There is a subset (4, 5) with sum 9.
+
+Input: set[] = {3, 34, 4, 12, 5, 2}, sum = 30
+Output: False
+There is no subset that add up to 30.
+```
+
+## 📈 Workflow of the script
+- `isSubsetSum` - Returns true if there is a subset of set[] with sum equal to given sum.
+- `main` - This is the driver code for this python script.
+
+## 📃 Explanation
+We will create a 2D array of `size (arr.size() + 1) * (target + 1)` of type boolean. The state `DP[i][j]` will be true if there exists a subset of elements from `A[0….i]` with sum value = `‘j’`. The approach for the problem is: 
+```
+if (A[i-1] > j)
+DP[i][j] = DP[i-1][j]
+else 
+DP[i][j] = DP[i-1][j] OR DP[i-1][j-A[i-1]]
+```
+1. This means that if current element has value greater than ‘current sum value’ we will copy the answer for previous cases
+2. And if the current sum value is greater than the `‘ith’` element we will see if any of previous states have already experienced the `sum=’j’` OR any previous states experienced a value `‘j – A[i]’` which will solve our purpose.
+
+## 🧮 Algorithm
+The below simulation will clarify the above approach: 
+```
+set[]={3, 4, 5, 2}
+target=6
+ 
+    0    1    2    3    4    5    6
+
+0   T    F    F    F    F    F    F
+
+3   T    F    F    T    F    F    F
+     
+4   T    F    F    T    T    F    F   
+      
+5   T    F    F    T    T    T    F
+
+2   T    F    T    T    T    T    T
+```
+
+## 💻 Input and Output 
+- **Test Case 1 :**
+
+![](https://github.com/abhisheks008/PyAlgo-Tree/blob/main/Dynamic%20Programming/Subset%20Sum%20Problem/Images/subset1.png)
+
+- **Test Case 2 :**
+
+![](https://github.com/abhisheks008/PyAlgo-Tree/blob/main/Dynamic%20Programming/Subset%20Sum%20Problem/Images/subset2.png)
+
+- **Test Case 3 :**
+
+![](https://github.com/abhisheks008/PyAlgo-Tree/blob/main/Dynamic%20Programming/Subset%20Sum%20Problem/Images/subset3.png)
+
+- **Test Case 3 :**
+
+![](https://github.com/abhisheks008/PyAlgo-Tree/blob/main/Dynamic%20Programming/Subset%20Sum%20Problem/Images/subset4.png)
+
+
+## ⏰ Time and Space complexity
+- **Time Complexity:** `O(sum*n)`, where sum is the ‘target sum’ and ‘n’ is the size of array. 
+- **Space Complexity:** `O(sum*n)`, as the size of 2-D array is `sum*n`.
+
+---------------------------------------------------------------
+## 🖋️ Author
+**Code contributed by, _Abhishek Sharma_, 2021 [@abhisheks008](github.com/abhisheks008)**
+
+[![forthebadge made-with-python](http://ForTheBadge.com/images/badges/made-with-python.svg)](https://www.python.org/)