# Questions tagged [recursion]

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### Pset3 Tideman: lock_pairs skips middle pair if it creates a cycle

I'm having issues figuring out how to solve this problem without using recursion (I'm not sure how to solve things recursively). Its a program that determines the winner of a Tideman election and I'm ...
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### Tideman lock_pairs recursion problem

I'm currently working on Pset3 Tideman and am stuck on the recursion part of lock_pairs function. I tried implementing an additional function to check for a cycle, and obviously, it's not working. ...
2k views

### Valgrind says “Invalid read of size 4” while freeing memory recursively in a trie

My PSET "mispelling" works fine and contains no memory leak but when I run the program with Valgrind it says Invalid read of size 4. My unload function calls a deleteTrie function which looks like ...
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### How h increases while executing for loop. In lecture3 recursion example

#include <cs50.h> #include <stdio.h> void draw(int h); int main(void) { // Get height of pyramid int height = get_int("Height: "); // Draw pyramid draw(height);...
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### lock_pairs skips final pair if it creates cycle

I have been working on the tideman problem from Problem Set 3. After multiple attempts, I have been able to pass all the required checks except one: "lock_pairs skips final pair if it creates ...
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### I don't understand how the collatz(n) recursive function works

If you watch the short on recursion in week2 2018, Doug explains how calculate the steps for the collatz conjecture. I don't understand how the solution he proposes can work: int collatz(int n) { ...
110 views

I haven't written any code yet, although I've written pseudocode for this problem, and I keep coming back to the issue of base case. I built a trie and now want to recursively unload it. I think I've ...
112 views

### How can I write a recursive function if that function's parameter is void? - pset5 - unload

Per the specification, we are not allowed to alter the declarations of load, check, size, or unload in dictionary.c or dictionary.h. Yet in Zamyla's walkthrough for unload, if one implements with a ...
197 views

### Pset5 Unload - Recursion with Tries - Fails Valgrind with apostrophes

I'm getting a strange problem in my unload() code, or more specifically the freeNode() recursive function that unload() calls. I think I have the recursive part of the function nailed; once free(...