Practice Questions for Recursion | Set 1 Last Updated : 20 Feb, 2023 Comments Improve Suggest changes Like Article Like Report Explain the functionality of the following functions. Question 1 C++ int fun1(int x, int y) { if (x == 0) return y; else return fun1(x - 1, x + y); } C int fun1(int x, int y) { if (x == 0) return y; else return fun1(x - 1, x + y); } Java static int fun1(int x, int y) { if (x == 0) return y; else return fun1(x - 1, x + y); } Python3 def fun1(x, y) : if (x == 0) : return y else : return fun1(x - 1, x + y) # This code is contributed by divyesh072019 C# static int fun1(int x, int y) { if (x == 0) return y; else return fun1(x - 1, x + y); } // This code is contributed by divyesh072019 JavaScript <script> function fun1(x, y) { if (x == 0) return y else return fun1(x - 1, x + y) } // This code is contributed by gottumukkalabobby </script> Answer: The function fun1() calculates and returns ((1 + 2 … + x-1 + x) +y), which is x(x+1)/2 + y. For example, if x is 5 and y is 2, then fun should return 15 + 2 = 17. Question 2 C++ // minimum index finder int minIndex(int arr[], int s, int e) { int sml = INT32_MAX; int mindex; for (int i = s; i < e; i++) { if (sml > arr[i]) { sml = arr[i]; mindex = i; } } return mindex; } void fun2(int arr[], int start_index, int end_index) { if (start_index >= end_index) return; int min_index; int temp; // minIndex() returns index of minimum value in // array arr[start_index...end_index] min_index = minIndex(arr, start_index, end_index); // swap the element at start_index and min_index swap(arr[start_index], arr[min_index]); fun2(arr, start_index + 1, end_index); } // This code is contributed by nishant_0073 C // minimum index finder int minIndex(int arr[], int s, int e) { int sml = INT32_MAX; int mindex; for (int i = s; i < e; i++) { if (sml > arr[i]) { sml = arr[i]; mindex = i; } } return mindex; } void fun2(int arr[], int start_index, int end_index) { if (start_index >= end_index) return; int min_index; int temp; // minIndex() returns index of minimum value in // array arr[start_index...end_index] min_index = minIndex(arr, start_index, end_index); temp = arr[start_index]; arr[start_index] = arr[min_index]; arr[min_index] = temp; fun2(arr, start_index + 1, end_index); } Java // minimum index finder static int minIndex(int arr[], int s, int e) { int sml = Integer.MAX_VALUE; int mindex = ; for (int i = s; i < e; i++) { if (sml > arr[i]) { sml = arr[i]; mindex = i; } } return mindex; } static void fun2(int arr[], int start_index, int end_index) { if (start_index >= end_index) return; int min_index; int temp; // minIndex() returns index of minimum value in // array arr[start_index...end_index] min_index = minIndex(arr, start_index, end_index); temp = arr[start_index]; arr[start_index] = arr[min_index]; arr[min_index] = temp; fun2(arr, start_index + 1, end_index); } // This code is contributed by nishant_0073 Python3 # Minimum index finder def minIndex(arr, s, e): sml = sys.maxsize mindex = 0 for i in range(s, e): if (sml > arr[i]): sml = arr[i] mindex = i return mindex def fun2(arr, start_index, end_index): if (start_index >= end_index): return # minIndex() returns index of minimum value in # array arr[start_index...end_index] min_index = minIndex(arr, start_index, end_index) arr[start_index], arr[min_index] = arr[min_index], arr[start_index] fun2(arr, start_index + 1, end_index) # This code is contributed by rag2127 C# // minimum index finder static int minIndex(int[] arr, int s, int e) { int sml = Int32.MaxValue; int mindex; for(int i = s; i < e; i++) { if(sml > arr[i]) { sml = arr[i]; mindex = i; } } return mindex; } static void fun2(int[] arr, int start_index, int end_index) { if(start_index >= end_index) { return; } int min_index; int temp; // minIndex() returns index of minimum value in // array arr[start_index...end_index] min_index = minIndex(arr, start_index, end_index); temp = arr[start_index]; arr[start_index] = arr[min_index]; arr[min_index] = temp; fun2(arr, start_index + 1, end_index); } // This code is contributed by avanitrachhadiya2155 JavaScript <script> //Javascript Implementation // minimum index finder function minIndex(arr, s, e) { var sml = Number.MAX_SAFE_INTEGER; var mindex; for (int i = s; i < e; i++) { if (sml > arr[i]) { sml = arr[i]; mindex = i; } } return mindex; } function fun2(arr, start_index, end_index) { if (start_index >= end_index) return; var min_index; var temp; // minIndex() returns index of minimum value in // array arr[start_index...end_index] min_index = minIndex(arr, start_index, end_index); // swap the element at start_index and min_index temp = arr[start_index]; arr[start_index] = arr[min_index]; arr[min_index] = temp; fun2(arr, start_index + 1, end_index); } // This code is contributed by shubhamsingh10 </script> Answer: The function fun2() is a recursive implementation of Selection Sort. Time complexity: O(N2) Auxiliary Space: O(1) Please write comments if you find any of the answers/codes incorrect, or you want to share more information about the topics discussed above. Comment More infoAdvertise with us Next Article Practice Questions for Recursion | Set 1 kartik Follow Improve Article Tags : DSA Recursion Practice Tags : Recursion Similar Reads Introduction to Recursion The process in which a function calls itself directly or indirectly is called recursion and the corresponding function is called a recursive function. A recursive algorithm takes one step toward solution and then recursively call itself to further move. The algorithm stops once we reach the solution 14 min read What is Recursion? Recursion is defined as a process which calls itself directly or indirectly and the corresponding function is called a recursive function.Example 1 : Sum of Natural Numbers Let us consider a problem to find the sum of natural numbers, there are several ways of doing that but the simplest approach is 8 min read Difference between Recursion and Iteration A program is called recursive when an entity calls itself. A program is called iterative when there is a loop (or repetition).Example: Program to find the factorial of a number C++ // C++ program to find factorial of given number #include<bits/stdc++.h> using namespace std; // ----- Recursion 6 min read Types of Recursions What is Recursion? The process in which a function calls itself directly or indirectly is called recursion and the corresponding function is called a recursive function. Using recursive algorithm, certain problems can be solved quite easily. 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This technique is commonly used in programming to solve problems that can be broken do 4 min read Difference Between Recursion and Induction Recursion and induction are fundamental ideas in computer science and mathematics that might be regularly used to solve problems regarding repetitive structures. Recursion is a programming technique in which a function calls itself to solve the problem, whilst induction is a mathematical proof techn 4 min read Like