some bugs and some minor tweak

Author: nisabmohd

src/Graphs/GraphGeneric.java

@@ -4,7 +4,6 @@
 
 public class GraphGeneric<T> {
 
-    // example for generic graph is present in dir -> ./GenericGraphExample.java
     private Map<Object, ArrayList<Object>> map;
     private boolean bidirectional;
 
@@ -44,20 +43,28 @@ public void addEdge(T start, T end) {
         }
     }
 
-    HashSet<T> vis;
 
-    public ArrayList<ArrayList<T>> bfs() {
+    public List<List<T>> bfs() {
+        HashSet<T> vis;
         vis = new HashSet<>();
-        ArrayList<ArrayList<T>> ans = new ArrayList<>();
+        List<List<T>> ans = new ArrayList<>();
         map.forEach((k, v) -> {
             if (!vis.contains(k)) {
-                ans.add(bfs((T) k));
+                ans.add(bfs((T) k, vis));
             }
         });
         return ans;
     }
 
-    public ArrayList<T> bfs(T source) {
+    public List<T> bfs(T source) {
+        if (!map.containsKey(source)) {
+            return new ArrayList<>();
+        }
+        HashSet<T> vis = new HashSet<>();
+        return this.bfs(source, vis);
+    }
+
+    private List<T> bfs(T source, HashSet<T> vis) {
         ArrayList<T> ans = new ArrayList<>();
         Queue<T> queue = new LinkedList<>();
         queue.add(source);
@@ -76,26 +83,27 @@ public ArrayList<T> bfs(T source) {
         return ans;
     }
 
-    public ArrayList<ArrayList<T>> dfs() {
-        ArrayList<ArrayList<T>> ans = new ArrayList<>();
+    public List<List<T>> dfs() {
+        List<List<T>> ans = new ArrayList<>();
         HashSet<T> visited = new HashSet<>();
         map.forEach((k, v) -> {
             if (!visited.contains(k)) {
                 ans.add(this.dfs((T) k, visited));
             }
         });
-
         return ans;
     }
 
-    public ArrayList<T> dfs(T source) { // return only a component of graph containing that source in it
+    // return only a component of graph containing that source in it
+    public List<T> dfs(T source) {
         if (!map.containsKey(source)) {
             return new ArrayList<>();
         }
+        HashSet<T> vis = new HashSet<>();
         return this.dfs(source, new HashSet<>());
     }
 
-    private ArrayList<T> dfs(T s, HashSet<T> visited) {
+    private List<T> dfs(T s, HashSet<T> visited) {
         ArrayList<T> ret = new ArrayList<>();
         ret.add(s);
         visited.add(s);
@@ -107,9 +115,9 @@ private ArrayList<T> dfs(T s, HashSet<T> visited) {
         return ret;
     }
 
-    @Override // returns adjacency map 
+    @Override // returns adjacency map
     public String toString() {
         return map.toString();
     }
 
-}
+}

src/Heaps/Heap.java

@@ -10,12 +10,12 @@ public class Heap<T extends Comparable<T>> {
 
     private int size = 0;
 
+    // Default as maxheap
     public Heap() {
         list.add(null);
         index = 0;
     }
 
-    // Default as maxheap
     // pass Comparator for min Heap
     // pass  Comparator.reverseOrder() for min heap
     public Heap(Comparator<T> comparator) {
@@ -59,25 +59,21 @@ public T poll() {
         T t = list.get(index);
         list.set(1, t);
         int i = 1;
-        while (i < index) {
+        while (i < index - 1) {
             int maxIndex = i, left = 2 * i, right = (2 * i) + 1;
-            if (left < index && comparator.compare(list.get(i), list.get(left)) > 0) {
+            if (left < index && comparator.compare(list.get(maxIndex), list.get(left)) < 0)
                 maxIndex = left;
-            }
-            if (right < index && comparator.compare(list.get(i), list.get(right)) > 0) {
+            if (right < index && comparator.compare(list.get(maxIndex), list.get(right)) < 0)
                 maxIndex = right;
-            }
             if (maxIndex != i) {
                 t = list.get(i);
                 list.set(i, list.get(maxIndex));
                 list.set(maxIndex, t);
                 i = maxIndex;
-            } else {
-                break;
-            }
-
+            } else break;
         }
         index--;
+        size--;
         return deleted;
     }
 
@@ -97,6 +93,10 @@ public void clear() {
         index = 0;
     }
 
+    public boolean isEmpty() {
+        return index == 0;
+    }
+
     @Override
     public String toString() {
         StringBuilder ans = new StringBuilder("[");
@@ -108,4 +108,4 @@ public String toString() {
         ans.append(list.get(i));
         return ans.append("]").toString();
     }
-}
+}

src/Lists/StackCustom.java renamed to src/Lists/Stacks.java

@@ -1,59 +1,56 @@
 package Lists;
 
-public class StackCustom<T> {
+public class Stacks<T> {
 
     private Object[] arr;
-    private int top = -1, size = 0;
+    private int top = -1;
     private final int DEFAULT_CAPACITY = 5;
     private boolean expand = false;
 
-    public StackCustom() {
+    public Stacks() {
+        // this creates a dynamic stack with no length bound
         arr = new Object[DEFAULT_CAPACITY];
         expand = true;
     }
 
-    public StackCustom(int initailCapacity) {
-        arr = new Object[initailCapacity];
+    public Stacks(int capacity) {
+        // this creates capacity bounded stack
+        arr = new Object[capacity];
     }
 
     private void doubleArr() {
+        // this method used internally for dynamic length of stack
         Object[] temp = new Object[2 * arr.length];
-        for (int i = 0; i < arr.length; i++) {
+        for (int i = 0; i < arr.length; i++)
             temp[i] = arr[i];
-        }
         arr = temp;
     }
 
-    public T push(T val) throws Exception {
+    public T push(T val) throws RuntimeException {
         if (top == arr.length - 1) {
-            if (expand) {
-                doubleArr();
-            } else {
-                throw new Exception("Stack Overflow");
-            }
+            if (expand) doubleArr();
+            else throw new RuntimeException("Stack Overflow");
         }
         arr[++top] = val;
         return (T) arr[top];
-
     }
 
-    public boolean empty() {
+    public boolean isEmpty() {
         return top == -1;
     }
 
-    public T peek() throws Exception {
-        if (top == -1) {
-            throw new Exception("Empty stack exception");
-        }
+    public int size() {
+        return this.top + 1;
+    }
+
+    public T peek() throws RuntimeException {
+        if (top == -1) throw new RuntimeException("Empty stack exception");
         return (T) arr[top];
     }
 
-    public T pop() throws Exception {
-        if (top == -1) {
-            throw new Exception("Empty stack exception");
-        }
-        T temp = (T) arr[top];
-        top--;
+    public T pop() throws RuntimeException {
+        if (top == -1) throw new RuntimeException("Empty stack exception");
+        T temp = (T) arr[top--];
         return temp;
     }
 
@@ -71,5 +68,4 @@ public String toString() {
         }
         return ret.toString();
     }
-
-}
+}

src/Trie/Trie.java

@@ -104,18 +104,6 @@ public void remove(String o) {
         node.isEndOfWord = false;
     }
 
-    // checks whether a prefix is present in Trie
-    public boolean startsWith(String prefix) {
-        TrieNode temp = root;
-        for (int i = 0; i < prefix.length(); i++) {
-            if (!temp.map.containsKey(prefix.charAt(i))) {
-                return false;
-            } else {
-                temp = temp.map.get(prefix.charAt(i));
-            }
-        }
-        return true;
-    }
 
     // When print is done to Trie toString metod is called
     @Override