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| 1 | +# 872. Leaf-Similar Trees |
| 2 | + |
| 3 | +- Difficulty: Easy. |
| 4 | +- Related Topics: Tree, Depth-First Search, Binary Tree. |
| 5 | +- Similar Questions: . |
| 6 | + |
| 7 | +## Problem |
| 8 | + |
| 9 | +Consider all the leaves of a binary tree, from left to right order, the values of those leaves form a **leaf value sequence****.** |
| 10 | + |
| 11 | + |
| 12 | + |
| 13 | + |
| 14 | + |
| 15 | +For example, in the given tree above, the leaf value sequence is `(6, 7, 4, 9, 8)`. |
| 16 | + |
| 17 | +Two binary trees are considered **leaf-similar** if their leaf value sequence is the same. |
| 18 | + |
| 19 | +Return `true` if and only if the two given trees with head nodes `root1` and `root2` are leaf-similar. |
| 20 | + |
| 21 | + |
| 22 | +Example 1: |
| 23 | + |
| 24 | + |
| 25 | + |
| 26 | +``` |
| 27 | +Input: root1 = [3,5,1,6,2,9,8,null,null,7,4], root2 = [3,5,1,6,7,4,2,null,null,null,null,null,null,9,8] |
| 28 | +Output: true |
| 29 | +``` |
| 30 | + |
| 31 | +Example 2: |
| 32 | + |
| 33 | + |
| 34 | + |
| 35 | +``` |
| 36 | +Input: root1 = [1,2,3], root2 = [1,3,2] |
| 37 | +Output: false |
| 38 | +``` |
| 39 | + |
| 40 | + |
| 41 | +**Constraints:** |
| 42 | + |
| 43 | + |
| 44 | + |
| 45 | +- The number of nodes in each tree will be in the range `[1, 200]`. |
| 46 | + |
| 47 | +- Both of the given trees will have values in the range `[0, 200]`. |
| 48 | + |
| 49 | + |
| 50 | + |
| 51 | +## Solution |
| 52 | + |
| 53 | +```javascript |
| 54 | +/** |
| 55 | + * Definition for a binary tree node. |
| 56 | + * function TreeNode(val, left, right) { |
| 57 | + * this.val = (val===undefined ? 0 : val) |
| 58 | + * this.left = (left===undefined ? null : left) |
| 59 | + * this.right = (right===undefined ? null : right) |
| 60 | + * } |
| 61 | + */ |
| 62 | +/** |
| 63 | + * @param {TreeNode} root1 |
| 64 | + * @param {TreeNode} root2 |
| 65 | + * @return {boolean} |
| 66 | + */ |
| 67 | +var leafSimilar = function(root1, root2) { |
| 68 | + var arr1 = []; |
| 69 | + var arr2 = []; |
| 70 | + getLeafNodes(root1, arr1); |
| 71 | + getLeafNodes(root2, arr2); |
| 72 | + return arr1.length === arr2.length |
| 73 | + && arr1.every((item, index) => item === arr2[index]); |
| 74 | +}; |
| 75 | + |
| 76 | +var getLeafNodes = function(root, result) { |
| 77 | + if (!root.left && !root.right) result.push(root.val); |
| 78 | + root.left && getLeafNodes(root.left, result); |
| 79 | + root.right && getLeafNodes(root.right, result); |
| 80 | +}; |
| 81 | +``` |
| 82 | + |
| 83 | +**Explain:** |
| 84 | + |
| 85 | +nope. |
| 86 | + |
| 87 | +**Complexity:** |
| 88 | + |
| 89 | +* Time complexity : O(n). |
| 90 | +* Space complexity : O(n). |
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