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| 1 | +/** |
| 2 | + * Definition for a binary tree node. |
| 3 | + * class TreeNode { |
| 4 | + * val: number |
| 5 | + * left: TreeNode | null |
| 6 | + * right: TreeNode | null |
| 7 | + * constructor(val?: number, left?: TreeNode | null, right?: TreeNode | null) { |
| 8 | + * this.val = (val===undefined ? 0 : val) |
| 9 | + * this.left = (left===undefined ? null : left) |
| 10 | + * this.right = (right===undefined ? null : right) |
| 11 | + * } |
| 12 | + * } |
| 13 | + */ |
| 14 | + |
| 15 | + |
| 16 | +/** |
| 17 | + * subTree๊ฐ root์ ํฌํจ๋๋์ง ํ์ธํ๋ ํจ์ |
| 18 | + * |
| 19 | + * @param {TreeNode | null} root - ์ฃผ์ด์ง ํธ๋ฆฌ |
| 20 | + * @param {TreeNode | null} subRoot - ํฌํจ๋๋์ง ํ์ธํ ํธ๋ฆฌ |
| 21 | + * @returns {boolean} - subRoot๊ฐ root์ ํฌํจ๋๋์ง ์ฌ๋ถ |
| 22 | + * |
| 23 | + * ์๊ฐ ๋ณต์ก๋: O(n * m) |
| 24 | + * - `isSameTree`๋ ๋ ํธ๋ฆฌ๊ฐ ๋์ผํ์ง ํ์ธํ๋๋ฐ O(m) ์๊ฐ์ด ๊ฑธ๋ฆผ (`m`: subRoot์ ๋
ธ๋ ์). |
| 25 | + * - `isSubtree`๋ `root`์ ๊ฐ ๋
ธ๋์์ `isSameTree`๋ฅผ ํธ์ถํ ์ ์์ (`n`: root์ ๋
ธ๋ ์). |
| 26 | + * - ๋ฐ๋ผ์ ์ต์
์ ๊ฒฝ์ฐ O(n * m). |
| 27 | + * |
| 28 | + * ๊ณต๊ฐ ๋ณต์ก๋: O(n) |
| 29 | + * - ์ฌ๊ท ํธ์ถ์ ๋ฐ๋ฅธ call stack ์ฌ์ฉ |
| 30 | + */ |
| 31 | +function isSubtree(root: TreeNode | null, subRoot: TreeNode | null): boolean { |
| 32 | + if (!subRoot) return true; |
| 33 | + if (!root) return false; |
| 34 | + |
| 35 | + const isSameTree = (treeA: TreeNode | null, treeB: TreeNode | null ): boolean => { |
| 36 | + // ๋ ํธ๋ฆฌ ๋ชจ๋ null ์ธ ๊ฒฝ์ฐ true |
| 37 | + if (!treeA && !treeB) return true; |
| 38 | + // ํ๋๋ง null ์ธ ๊ฒฝ์ฐ false |
| 39 | + if (!treeA || !treeB) return false; |
| 40 | + // val์ด ๋ค๋ฅธ ๊ฒฝ์ฐ false |
| 41 | + if (treeA.val !== treeB.val) return false; |
| 42 | + return isSameTree(treeA.left, treeB.left) && isSameTree(treeA.right, treeB.right) |
| 43 | + } |
| 44 | + |
| 45 | + // ํ์ฌ ๋
ธ๋์์ subRoot๊ฐ ์์๋๋ ํธ๋ฆฌ์ธ์ง ํ์ธ |
| 46 | + if (isSameTree(root, subRoot)) return true; |
| 47 | + |
| 48 | + // ์ผ์ชฝ, ์ค๋ฅธ์ชฝ ํ์ ํธ์ subRoot๊ฐ ํฌํจ๋๋์ง ํ์ธ |
| 49 | + return isSubtree(root.left, subRoot) || isSubtree(root.right, subRoot) |
| 50 | +}; |
| 51 | + |
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