Programmers Never Sleep,They just go offline

                 Problem Statement:-  Given the  root  of a binary tree, invert the tree, and return  its root .                 Solution

              Problem statement:- Given the  root  of a binary tree,  check whether it is a mirror of itself  (i.e., symmetric around its center).                           Solution:-

 

 

 

 

 

 

 

 

import java . util . HashMap ; import java . util . Map ; class TwoSum { // Time complexity: O(n) private static int [ ] findTwoSum ( int [ ] nums , int target ) { Map < Integer , Integer > numMap = new HashMap < > ( ) ; for ( int i = 0 ; i < nums . length ; i ++ ) { int complement = target - nums [ i ] ; if ( numMap . containsKey ( complement ) ) { return new int [ ] { numMap . get ( complement ) , i } ; } else { numMap . put ( nums [ i ] , i ) ; } } return new int [ ] { } ; } }