From 08cba51fb38e276062b0c9791d7e0ee494ffa903 Mon Sep 17 00:00:00 2001
From: Yash9276 <123647814+Yash9276@users.noreply.github.com>
Date: Fri, 27 Oct 2023 14:47:30 +0530
Subject: [PATCH] Added Insertion sort, palindrome code as well as Subset
 generator code  (#88)

* added  InsertionSort sort

* added Palindrome.sol which checks whether steing is palindrome or not

* added Subset.sol which finds total number of subsets in array

* Update src/Maths/Palindrome.sol

---------

Co-authored-by: @Yash9276 <yashkudnar519@gmail.com>
Co-authored-by: Maxime Kubik <50140834+mkubdev@users.noreply.github.com>
---
 src/Maths/Palindrome.sol    | 24 ++++++++++++++++++++++
 src/Maths/Subset.sol        | 33 ++++++++++++++++++++++++++++++
 src/Sorts/InsertionSort.sol | 40 +++++++++++++++++++++++++++++++++++++
 3 files changed, 97 insertions(+)
 create mode 100644 src/Maths/Palindrome.sol
 create mode 100644 src/Maths/Subset.sol
 create mode 100644 src/Sorts/InsertionSort.sol

diff --git a/src/Maths/Palindrome.sol b/src/Maths/Palindrome.sol
new file mode 100644
index 0000000..fc656fb
--- /dev/null
+++ b/src/Maths/Palindrome.sol
@@ -0,0 +1,24 @@
+// SPDX-License-Identifier: MIT
+pragma solidity ^0.8.0;
+
+contract PalindromeChecker {
+    // Function to check if a given string is a palindrome
+    function isPalindrome(string memory str) public pure returns (bool) {
+        // Convert the input string to a bytes array
+        bytes memory bytesStr = bytes(str);
+        // Get the length of the string
+        uint256 len = bytesStr.length;
+
+        // Loop through the first half of the string
+        for (uint256 i = 0; i < len / 2; i++) {
+            // Compare characters from the start and end of the string
+            if (bytesStr[i] != bytesStr[len - 1 - i]) {
+                // If characters don't match, return false (not a palindrome)
+                return false;
+            }
+        }
+        
+        // If the loop completes without finding mismatches, return true (a palindrome)
+        return true;
+    }
+}
diff --git a/src/Maths/Subset.sol b/src/Maths/Subset.sol
new file mode 100644
index 0000000..6f51f84
--- /dev/null
+++ b/src/Maths/Subset.sol
@@ -0,0 +1,33 @@
+// SPDX-License-Identifier: MIT
+pragma solidity ^0.8.0;
+
+contract SubsetGenerator {
+    // Function to generate all possible subsets of an input array
+    function generateSubsets(uint[] memory arr) public pure returns (uint[][] memory) {
+        uint n = arr.length; // Get the length of the input array
+        uint[][] memory subsets = new uint[][](2**n); // Initialize an array to store subsets
+        
+        // Loop through all possible binary combinations
+        for (uint i = 0; i < 2**n; i++) {
+            uint[] memory subset = new uint[](n); // Create an array for the current subset
+            uint count = 0; // Counter for the number of elements in the subset
+            
+            // Loop through the bits of the current binary combination
+            for (uint j = 0; j < n; j++) {
+                // Check if the j-th bit of i is set to 1
+                if ((i & (1 << j)) != 0) {
+                    subset[count] = arr[j]; // Include the element in the subset
+                    count++; // Increment the count of elements in the subset
+                }
+            }
+            
+            // Create a new array to store the final subset (with only the necessary elements)
+            subsets[i] = new uint[](count);
+            for (uint k = 0; k < count; k++) {
+                subsets[i][k] = subset[k]; // Copy the elements to the final subset
+            }
+        }
+        
+        return subsets; // Return the array of subsets
+    }
+}
diff --git a/src/Sorts/InsertionSort.sol b/src/Sorts/InsertionSort.sol
new file mode 100644
index 0000000..fb73388
--- /dev/null
+++ b/src/Sorts/InsertionSort.sol
@@ -0,0 +1,40 @@
+// SPDX-License-Identifier: MIT
+pragma solidity ^0.8.0;
+
+/**
+ * @title InsertionSOrt
+ * @author [Yash9276](https://github.com/Yash9276)
+ * @notice A contract that implements the insertion sort algorithm.
+ * @dev It repeatedly takes an element from the unsorted part and inserts
+ * it into its correct position in the sorted part of the array, 
+*shifting the elements if necessary. It has an average and worst-case time complexity of O(n^2) but
+* is efficient for small datasets or partially sorted data.
+   
+ */
+
+contract InsertionSort {
+    /* @notice Sorts the given array in increasing order.
+     @param input The array to sort.
+     @return output The resulting sorted array in increasing order
+     */
+
+    function sort(uint256[] memory myArray)
+        public
+        pure
+        returns (uint256[] memory)
+    {
+        uint256 n = myArray.length;
+        for (uint256 i = 1; i < n; i++) {
+            uint256 key = myArray[i];
+            int256 j = int256(i - 1);
+
+            while (j >= 0 && int256(myArray[uint256(j)]) > int256(key)) {
+                myArray[uint256(j + 1)] = myArray[uint256(j)];
+                j--;
+            }
+
+            myArray[uint256(j + 1)] = key;
+        }
+        return myArray;
+    }
+}