Finished all tests

src/Practice.java

@@ -1,3 +1,5 @@
+import java.util.HashMap;
+import java.util.HashSet;
 import java.util.Map;
 import java.util.Set;
 
@@ -11,7 +13,17 @@ 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 count = 0;
+
+
+       for(int i = 0; i < nums.length; i++){
+           if(nums[i] % 2 != 0){
+               count += nums[i];
+           }
+       }
+       return count;
+
     }
 
     /**
@@ -26,7 +38,23 @@ public static int oddSum(int[] nums) {
      * @throws NullPointerException if words is null
      */
     public static String shortestWord(Set<String> words) {
-        return null;
+        if(words.size() == 0) throw new IllegalArgumentException();
+        if(words == null) throw new NullPointerException();
+
+
+        String shortest = null;
+
+
+        for (String word : words) {
+            if(shortest == null) shortest = word;
+            else if(word.length() < shortest.length()) shortest = word;
+            else if(word.length() == shortest.length()){
+                if(word.compareTo(shortest) < 0) shortest = word;
+            }
+        }
+
+
+        return shortest;
     }
 
     /**
@@ -39,7 +67,13 @@ 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();
+        Set<String> set = new HashSet<>();
+
+        for (String name : ages.keySet()) {
+            if(ages.get(name) >= 18) set.add(name);
+        }
+        return set;
     }
 
     /**
@@ -50,7 +84,16 @@ 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> temp = head;
+        int max = Integer.MIN_VALUE;
+
+        while(temp!= null){
+            if(temp.data > max) max = temp.data;
+            temp = temp.next;
+        }
+        return max;
     }
 
     /**
@@ -67,7 +110,22 @@ 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;
+        Map<T, Integer> map = new HashMap<>();
+        if(head == null) return map;
+
+        ListNode<T> temp = head;
+
+        while(temp != null){
+            if(!map.containsKey(temp.data)){
+                map.put(temp.data, map.getOrDefault(temp.data, 0)+1);
+            }else{
+                map.put(temp.data, map.getOrDefault(temp.data, 0)+1);
+            }
+
+            temp = temp.next;
+        }
+
+        return map;
     }
 
 
@@ -80,7 +138,12 @@ 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;
+
+        int left = levelCount(root.left);
+        int right = levelCount(root.right);
+
+        return Math.max(left, right) + 1;
     }
 
 
@@ -108,7 +171,15 @@ 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;
+        return sumAtLevel(root, level,1);
+    }
+
+    private static int sumAtLevel(BinaryTreeNode<Integer> root, int level, int curLvl){
+        if(root == null) return 0;
+
+        if(curLvl == level) return root.data;
+
+        return sumAtLevel(root.left, level, curLvl+1) + sumAtLevel(root.right, level, curLvl+1);
     }
 
 
@@ -123,7 +194,23 @@ 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 sumTree = sumOfTree(root);
+        int sumList = 0;
+
+        ListNode<Integer> temp = head;
+        while(temp != null){
+            sumList += temp.data;
+            temp = temp.next;
+        }
+
+        return sumList == sumTree;
+    }
+
+    private static int sumOfTree(BinaryTreeNode<Integer> root){
+        if(root == null) return 0;        
+        int sum = sumOfTree(root.left) + sumOfTree(root.right) + root.data;
+
+        return sum;
     }
 
     /**
@@ -136,7 +223,21 @@ public static boolean sumMatch(BinaryTreeNode<Integer> root, ListNode<Integer> h
      * @return the sum of all the vertices
      */
     public static int graphSum(Vertex<Integer> start) {
-        return 0;
+        Set<Vertex<Integer>> visited = new HashSet<>();
+        return graphSum(start, visited);
+    }
+
+    private static int graphSum(Vertex<Integer> start, Set<Vertex<Integer>> visited){
+        if(start == null || visited.contains(start)) return 0;
+
+        visited.add(start);
+        int total = start.data;
+
+        for(Vertex<Integer> neighbor : start.neighbors){
+            total += graphSum(neighbor, visited);
+        }
+
+        return total;
     }
 
     /**
@@ -148,6 +249,22 @@ public static int graphSum(Vertex<Integer> start) {
      * @return the count of vertices with outdegree 0
      */
     public static int sinkCount(Vertex<Integer> start) {
-        return 0;
+        Set<Vertex<Integer>> visited = new HashSet<>();
+        return sinkCount(start, visited);
+    }
+
+    private static int sinkCount(Vertex<Integer> start, Set<Vertex<Integer>> visited){
+        if(start == null || visited.contains(start)) return 0;
+
+        visited.add(start);
+        int sink = 0;
+
+        if(start.neighbors.isEmpty()) sink++;
+
+        for (Vertex<Integer> neighbor : start.neighbors) {
+            sink += sinkCount(neighbor, visited);
+        }
+
+        return sink;
     }
 }