### 617 Merge Two Binary Trees

```/**
*
* Ashish Patel
* e: ashishsushilPatel@gmail.com
* w: https://ashish.me
*
*/

/*
* Given two binary trees and imagine that when you put one of them to cover the other,
* some nodes of the two trees are overlapped while the others are not.
*
* You need to merge them into a new binary tree. The merge rule is that if two nodes
* overlap, then sum node values up as the new value of the merged node. Otherwise,
* the NOT null node will be used as the node of new tree.
*/

function TreeNode(val) {
this.val = val
this.left = this.right = null
}

const mergeTwoBinaryTrees = (t1, t2) => {
if (!t1) return t2
if (!t2) return t1
t1.val += t2.val
t1.left = mergeTwoBinaryTrees(t1.left, t2.left)
t1.right = mergeTwoBinaryTrees(t1.right, t2.right)
return t1
}

test('mergeTwoBinaryTrees', () => {
const t1 = new TreeNode(1)
t1.right = new TreeNode(2)
t1.left = new TreeNode(3)
t1.left.left = new TreeNode(5)

const t2 = new TreeNode(2)
t2.right = new TreeNode(3)
t2.right.right = new TreeNode(7)
t2.left = new TreeNode(1)
t2.left.right = new TreeNode(4)

const t3 = new TreeNode(3)
t3.right = new TreeNode(5)
t3.right.right = new TreeNode(7)
t3.left = new TreeNode(4)
t3.left.left = new TreeNode(5)
t3.left.right = new TreeNode(4)
expect(mergeTwoBinaryTrees(t1, t2)).toEqual(t3)
})```

Created 2020-12-05T20:34:20+05:30, updated 2020-12-05T20:35:54+05:30 · History · Edit