CC4.3.java

/*4.3 Given a sorted (increasing order) array with unique integer elements, write an algorithm to create a binary search tree 
with minimal height.*/

public class Solution {
    public TreeNode arrayToBST(int[] A) {
        return buildTree(A, 0, A.length);
    }
    public TreeNode buildTree(int[] A, int s, int e) {
        if(s>=e) return null;
        int mid = (s+e) >> 1;
        TreeNode root = new TreeNode(A[mid]);
        root.left = buildTree(A, s, mid);
        root.right = buildTree(A, mid+1, e);
        return root;
    }
}