Added 2 solutions & updated 1 solution

varunu28 · varunu28 · commit 7e9c8e44d360 · 2019-09-15T08:20:07.000-07:00
diff --git a/Easy/Maximum Number of Balloons.java b/Easy/Maximum Number of Balloons.java
@@ -0,0 +1,15 @@
+class Solution {
+    public int maxNumberOfBalloons(String text) {
+        Map<Character, Integer> map = new HashMap<>();
+        for (Character c : text.toCharArray()) {
+            map.put(c, map.getOrDefault(c, 0) + 1);
+        }
+        int maxCount = 0;
+        maxCount = map.getOrDefault('l', 0) / 2;
+        maxCount = Math.min(map.getOrDefault('o', 0) / 2, maxCount);
+        maxCount = Math.min(map.getOrDefault('b', 0), maxCount);
+        maxCount = Math.min(map.getOrDefault('a', 0), maxCount);
+        maxCount = Math.min(map.getOrDefault('n', 0), maxCount);
+        return maxCount;
+    }
+}
diff --git a/Easy/Subtree of Another Tree.java b/Easy/Subtree of Another Tree.java
@@ -9,24 +9,25 @@
  */
 class Solution {
     public boolean isSubtree(TreeNode s, TreeNode t) {
-        return traverseAndString(s).contains(traverseAndString(t));
-    }
-    
-    public String traverseAndString(TreeNode root) {
-        StringBuilder res = new StringBuilder();
-        traverse(root, res);
-        return res.toString();
+        if (s == null) {
+            return false;
+        }
+        if (helper(s, t)) {
+            return true;
+        }
+        return isSubtree(s.left, t) || isSubtree(s.right, t);
     }
     
-    public void traverse(TreeNode root, StringBuilder res) {
-        
-        if (root == null) {
-            res.append("-");
-            return;
+    private boolean helper(TreeNode s, TreeNode t) {
+        if (s == null && t == null) {
+            return true;
+        }
+        if ((s == null && t != null) || (s != null && t == null)) {
+            return false;
+        }
+        if (s.val != t.val) {
+            return false;
         }
-        
-        traverse(root.left, res);
-        traverse(root.right, res);
-        res.append(String.valueOf(root.val) + ",");
+        return helper(s.left, t.left) && helper(s.right, t.right);
     }
 }
diff --git a/Medium/Reverse Substrings Between Each Pair of Parentheses.java b/Medium/Reverse Substrings Between Each Pair of Parentheses.java
@@ -0,0 +1,17 @@
+class Solution {
+    public String reverseParentheses(String s) {
+        int start = 0;
+        int end = 0;
+        for (int i = 0; i < s.length(); i++) {
+            if (s.charAt(i) == '(') {
+                start = i;
+            }
+            if (s.charAt(i) == ')') {
+                end = i;
+                StringBuilder sb = new StringBuilder(s.substring(start + 1, end)).reverse();
+                return reverseParentheses(s.substring(0, start) + sb.toString() + s.substring(end + 1));
+            }
+        }
+        return s;
+    }
+}
