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late-night coding #19

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2a092f4
late-night coding
Zeta1313 Apr 9, 2026
64825f5
Just realized that I didn't actually make the actual commit, my bad
Zeta1313 Apr 9, 2026
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116 changes: 104 additions & 12 deletions src/Practice.java
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Original file line number Diff line number Diff line change
@@ -1,3 +1,5 @@
import java.util.HashMap;
import java.util.HashSet;
import java.util.List;
import java.util.Map;
import java.util.Set;
Expand All @@ -12,7 +14,14 @@ public class Practice {
* @return the sum of the odd numbers in the array
*/
public static int oddSum(int[] nums) {
return 0;
if (nums == null) return 0;
int output = 0;
for (int i: nums) {
if (i%2!=0) {
output = output + i;
}
}
return output;
}

/**
Expand All @@ -27,7 +36,15 @@ public static int oddSum(int[] nums) {
* @throws NullPointerException if words is null
*/
public static String shortestWord(Set<String> words) {
return null;
if (words == null) throw new NullPointerException();
if (words.isEmpty()) throw new IllegalArgumentException();
String output = "pneumonoultramicroscopicsilicovolcanoconiosis";
for (String x : words) {
if (x.length() < output.length() || (x.length() == output.length() && x.compareTo(output) < 0)) {
output = x;
}
}
Comment on lines +41 to +46
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@auberonedu auberonedu Apr 9, 2026

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What would happen if our shortest word was "bababadalgharaghtakamminarronnkonnbronntonnerronntuonnthunntrovarrhounawnskawntoohoohoordenenthurnuk" (the first 100-letter-long thunderword in the modernist classic "Finnegans Wake")? Can you think of how you could change your code to be more robust?

return output;
}

/**
Expand All @@ -40,7 +57,14 @@ public static String shortestWord(Set<String> words) {
* @throws NullPointerException if ages is null
*/
public static Set<String> adults(Map<String, Integer> ages) {
return null;
if (ages == null) throw new NullPointerException();
HashSet output = new HashSet<>();
for (String i : ages.keySet()) {
if (ages.get(i) >= 18) {
output.add(i);
}
}
return output;
}

/**
Expand All @@ -51,7 +75,19 @@ public static Set<String> adults(Map<String, Integer> ages) {
* @throws IllegalArgumentException if head is null
*/
public static int biggestNumber(ListNode<Integer> head) {
return 0;
if (head == null) throw new IllegalArgumentException();

ListNode<Integer> current = head;
int output = current.data;

while (current != null) {
if (current.data > output) {
output = current.data;
}
current = current.next;
}

return output;
}

/**
Expand All @@ -68,7 +104,18 @@ public static int biggestNumber(ListNode<Integer> head) {
* @return a frequency map of values in the list
*/
public static <T> Map<T, Integer> frequencies(ListNode<T> head) {
return null;
HashMap <T, Integer> output = new HashMap<>();
ListNode<T> current = head;
while (current!=null) {
if (output.containsKey(current.data)) {
output.put(current.data, output.get(current.data) + 1);
}
else {
output.put(current.data, 1);
}
current = current.next;
}
return output;
}


Expand All @@ -81,7 +128,12 @@ public static <T> Map<T, Integer> frequencies(ListNode<T> head) {
* @return the number of levels in the tree
*/
public static int levelCount(BinaryTreeNode<?> root) {
return 0;
if (root == null) return 0;
if (root.left == null && root.right == null) return 1;
int x = levelCount(root.left);
int y = levelCount(root.right);
if (x > y) return x+1;
else return y+1;
}


Expand Down Expand Up @@ -109,7 +161,9 @@ public static int levelCount(BinaryTreeNode<?> root) {
* @return the sum of the nodes at the given level
*/
public static int sumAtLevel(BinaryTreeNode<Integer> root, int level) {
return 0;
if (root == null) return 0;
if (level == 1) return root.data;
return sumAtLevel(root.left, level-1) + sumAtLevel(root.right, level-1);
}


Expand All @@ -124,7 +178,18 @@ public static int sumAtLevel(BinaryTreeNode<Integer> root, int level) {
* @return true if the sums are equal, false otherwise
*/
public static boolean sumMatch(BinaryTreeNode<Integer> root, ListNode<Integer> head) {
return false;
int output = 0;
ListNode<Integer> current = head;
while (current != null) {
output += current.data;
current = current.next;
}
return output == sumMatchHelper(root);
}

public static int sumMatchHelper(BinaryTreeNode<Integer> root) {
if (root == null) return 0;
return root.data + sumMatchHelper(root.left) + sumMatchHelper(root.right);
}

/**
Expand All @@ -136,7 +201,12 @@ public static boolean sumMatch(BinaryTreeNode<Integer> root, ListNode<Integer> h
* @return the sum of all the tree's values
*/
public static int nbSum(TreeNode<Integer> root) {
return 0;
if (root == null) return 0;
int output = 0;
for (TreeNode x : root.children) {
output = output + nbSum(x);
}
return output+root.data;
}

/**
Expand Down Expand Up @@ -167,9 +237,17 @@ public static int nbSum(TreeNode<Integer> root) {
* @param root the root of the tree
* @return the count of nodes that do not have siblings, EXCLUDING THE ROOT
*/
public static int onlyChildCount(TreeNode<?> root) {
return 0;
public static <T> int onlyChildCount(TreeNode<T> root) {
if (root == null) return 0;
int count = 0;
for (TreeNode<T> child : root.children) {
if (root.children.size() == 1) {
count += 1;
}
count += onlyChildCount(child);
}
return count;
}

/**
* Returns the maximum depth of the tree.
Expand Down Expand Up @@ -206,6 +284,20 @@ public static int onlyChildCount(TreeNode<?> root) {
* @return the depth of the tree, or 0 if the tree is null or the root is not present in the tree
*/
public static <T> int maxDepth(Map<T, List<T>> tree, T root) {
return 0;
if (tree == null) return 0;
if (!tree.containsKey(root)) return 0;
if (root == null) return 0;
return maxDepthHelper(tree, root);
}

public static <T> int maxDepthHelper(Map<T, List<T>> tree, T root) {
List<T> children = tree.get(root);
if (children == null || children.isEmpty()) return 1;
int output = 0;
for (T x : children) {
int y = maxDepthHelper(tree, x);
if (output < y) output = y;
}
return output + 1;
}
}