Practice Questions for Recursion | Set 3
Explain the functionality of below recursive functions.
Question 1
C++
void fun1(int n) { int i = 0; if (n > 1) fun1(n - 1); for (i = 0; i < n; i++) cout << " * "; } // This code is contributed by shubhamsingh10 |
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C
void fun1(int n) { int i = 0; if (n > 1) fun1(n-1); for (i = 0; i < n; i++) printf(" * "); } |
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Java
static void fun1(int n) { int i = 0; if (n > 1) fun1(n - 1); for (i = 0; i < n; i++) System.out.print(" * "); } // This code is contributed by shubhamsingh10 |
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Python3
def fun1(n): i = 0 if (n > 1): fun1(n - 1) for i in range(n): print(" * ",end="") # This code is contributed by shubhamsingh10 |
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C#
static void fun1(int n) { int i = 0; if (n > 1) fun1(n-1); for (i = 0; i < n; i++) Console.Write(" * "); } // This code is contributed by shubhamsingh10 |
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Answer: Total numbers of stars printed is equal to 1 + 2 + …. (n-2) + (n-1) + n, which is n(n+1)/2.
Question 2
C++
#define LIMIT 1000 void fun2(int n) { if (n <= 0) return; if (n > LIMIT) return; cout << n <<" "; fun2(2*n); cout << n <<" "; } // This code is contributed by shubhamsingh10 |
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C
#define LIMIT 1000 void fun2(int n) { if (n <= 0) return; if (n > LIMIT) return; printf("%d ", n); fun2(2*n); printf("%d ", n); } |
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Java
int LIMIT = 1000; void fun2(int n) { if (n <= 0) return; if (n > LIMIT) return; System.out.print(String.format("%d ", n)); fun2(2 * n); System.out.print(String.format("%d ", n)); } |
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Python3
LIMIT = 1000def fun2(n): if (n <= 0): return if (n > LIMIT): return print(n, end=" ") fun2(2 * n) print(n, end=" ") # This code is contributed by shubhamsingh10 |
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C#
int LIMIT = 1000 void fun2(int n) { if (n <= 0) return; if (n > LIMIT) return; Console.Write(n+" "); fun2(2*n); Console.Write(n+" "); } // This code is contributed by Shubhamsingh10 |
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Answer: For a positive n, fun2(n) prints the values of n, 2n, 4n, 8n … while the value is smaller than LIMIT. After printing values in increasing order, it prints same numbers again in reverse order. For example fun2(100) prints 100, 200, 400, 800, 800, 400, 200, 100.
If n is negative, the function is returned immediately.
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