chore(CPlusPlus): add linear search for recursion and two dimension array (#630)

algorithms/CPlusPlus/README.md

@@ -29,6 +29,7 @@
 - [Merge two sorted array without using extraspace](Arrays/merge-two-sorted-array.cpp)
 - [All unique triplet that sum up to given value](Arrays/three-sum.cpp)
 - [Next permutation](Arrays/next-permutation.cpp)
+
 ## Dynamic-Programming
 
 - [Longest Common Subsequence](Dynamic-Programming/longest-common-subsequence.cpp)
@@ -77,6 +78,7 @@
 - [Ternary Search](Searching/Ternary-search.cpp)
 - [Interpolation Search](Searching/interpolation-search.cpp)
 - [Exponential Search](Searching/exponential-search.cpp)
+- [Linear search in 2D array](Searching/linear-search-in-2d.cpp)
 
 ## Stacks
 
@@ -176,3 +178,4 @@
 - [Array sorted or not](Recursion\array-sorted-or-not.cpp)
 - [Product of two numbers](Recursion\product-of-numbers.cpp)
 - [Product of digits in a number](Recursion\product-of-digits.cpp)
+- [Linear search using recursion](Recursion/linear-search.cpp)

algorithms/CPlusPlus/Recursion/linear-search.cpp

@@ -0,0 +1,48 @@
+/*
+Description: linear search using recursion
+
+Time Complexity: O(n) where n is the number of elements in the array
+*/
+
+#include <iostream>
+#include <vector>
+using namespace std;
+
+//function starts
+int linearSearch(vector<int> arr, int i, int n, int target)
+{
+    //base case
+    if (i == n)
+    {
+        return -1;
+    }
+    //if the ith element in the array is equal to the target, return the index
+    if (arr[i] == target)
+    {
+        return i;
+    }
+    //recursive function call
+    //i refers to the index that we will need to check the element in the array
+    //at every recursive call we will increment the i by 1
+    return linearSearch(arr, i + 1, n, target);
+}
+
+//main starts
+int main()
+{
+    vector<int> arr = {1, 2, 3, 4, 5};
+    int n = arr.size();
+    int target = 3;
+    cout << linearSearch(arr, 0, n, target);
+    return 0;
+}
+
+/*
+Input:
+arr = [1,2,3,4,5]
+target = 3
+
+Output:
+2
+
+*/

algorithms/CPlusPlus/Searching/linear-search-in-2d.cpp

@@ -0,0 +1,55 @@
+/*
+Description: program to perform linear search in 2d array
+
+Time complexity: O (m*n) where m is the number of rows and n refers to the number of columns
+*/
+
+#include <iostream>
+#include <vector>
+using namespace std;
+
+//function starts
+void linearSearch(vector<vector<int>> arr, int target)
+{
+    //for every row
+    for (int i = 0; i < arr.size(); i++)
+    {
+        //for every element in the row, i.e column
+        for (int j = 0; j < arr[i].size(); j++)
+        {
+            //check if the element in the array is equal to the target
+            if (arr[i][j] == target)
+            {
+                cout << i << " " << j; //print it
+                return;
+            }
+        }
+    }
+    cout << "Element not found"; //else print element not found
+}
+
+//main starts
+int main()
+{
+    vector<vector<int>> arr = {
+        {1, 2, 3},
+        {4, 5, 6},
+        {7, 8, 9}}; //array
+
+    int target = 9;            //element need to be search
+    linearSearch(arr, target); //calling the function
+
+    return 0;
+}
+
+/*
+Input:
+arr = [
+    [1,2,3],
+    [4,5,6],
+    [7,8,9]
+]
+target = 9
+
+Output: 2 2
+*/