Two Sum IV - Input is a BST Solution Added in java language.

Leetcode -14 Days Study Plan to Crack Algo (Solutions)/Study Plan 1 - (Algorithm I)/Day 1/Java/Binary Search.java

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+class Solution {
+    public int search(int[] nums, int target) {
+
+        int start = 0;
+        int end = nums.length-1;
+
+        while(start<=end){
+
+            int mid = start+end>>>1;
+
+            if(nums[mid]==target){
+                return mid;
+            }else if(nums[mid]<target){
+                start = mid+1;
+            }else end = mid-1;
+
+        }
+
+        return -1;
+    }
+}

Leetcode -14 Days Study Plan to Crack Algo (Solutions)/Study Plan 1 - (Algorithm I)/Day 1/Java/First Bad Version.java

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+/* The isBadVersion API is defined in the parent class VersionControl.
+      boolean isBadVersion(int version); */
+
+public class Solution extends VersionControl {
+    public int firstBadVersion(int n) {
+
+        int start = 1;
+        int end = n;
+
+        while(start<end){
+            int mid = start+end>>>1;
+
+            if(isBadVersion(mid)){
+                end = mid;
+            }else start = mid+1;
+
+        }
+
+        return start;
+    }
+}

Leetcode -14 Days Study Plan to Crack Algo (Solutions)/Study Plan 1 - (Algorithm I)/Day 1/Java/Search Insert Position.java

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+class Solution {
+    public int searchInsert(int[] nums, int target) {
+
+        int start = 0;
+        int end = nums.length-1;
+
+        while(start<=end){
+
+            int mid = start+end>>>1;
+
+            if(nums[mid]==target) return mid;
+            else if(target<nums[mid]){
+                end = mid-1;
+            }else{
+                start = mid+1;
+            }
+
+        }
+
+
+        return start;
+    }
+}

Two Sum IV - Input is a BST.java

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+/**
+ * Definition for a binary tree node.
+ * public class TreeNode {
+ *     int val;
+ *     TreeNode left;
+ *     TreeNode right;
+ *     TreeNode() {}
+ *     TreeNode(int val) { this.val = val; }
+ *     TreeNode(int val, TreeNode left, TreeNode right) {
+ *         this.val = val;
+ *         this.left = left;
+ *         this.right = right;
+ *     }
+ * }
+ */
+class Solution {
+    public boolean findTarget(TreeNode root, int k) {
+
+        if(root.left==null && root.right==null) return false;
+
+        Set<Integer> set = new HashSet<>();
+        getVals(root,set);
+
+        for(int i:set){
+            if(set.contains(k-i) && i!=k-i) return true;
+        }
+
+            return false;
+    }
+
+    void getVals(TreeNode root, Set<Integer> set){
+
+        if(root==null) return;
+
+        set.add(root.val);
+        getVals(root.left,set);
+        getVals(root.right,set);
+
+    }
+
+}