Practice Questions for Recursion | Set 1
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);} |
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C++
int fun1(int x, int y){ if (x == 0) return y; else return fun1(x - 1, x + y);} |
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Java
static int fun1(int x, int y){ if (x == 0) return y; else return fun1(x - 1, x + y);} |
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Python3
def fun1(x, y) : if (x == 0) : return y else : return fun1(x - 1, x + y)# This code is contributed by divyesh072019 |
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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 |
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Answer: The function fun() 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 finderint 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 |
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C
// minimum index finderint 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);} |
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Java
// minimum index finderstatic 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 |
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Python3
# Minimum index finderdef 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 mindexdef 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 |
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C#
// minimum index finderstatic 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 |
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Answer: The function fun2() is a recursive implementation of Selection Sort.
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