100. Same Tree.md

100. Same Tree

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leetcode Daily Challenge on July 13th, 2020.

leetcode-cn Daily Challenge on August 7th, 2020.

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Difficulty : Easy

Related Topics : DFS、Tree

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Given two binary trees, write a function to check if they are the same or not.

Two binary trees are considered the same if they are structurally identical and the nodes have the same value.

Example 1:

Input:     1         1
          / \       / \
         2   3     2   3

        [1,2,3],   [1,2,3]

Output: true

Example 2:

Input:     1         1
          /           \
         2             2

        [1,2],     [1,null,2]

Output: false

Example 3:

Input:     1         1
          / \       / \
         2   1     1   2

        [1,2,1],   [1,1,2]

Output: false

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Solution

• mine
  • Java
    • DFS & Recursion Runtime: 0 ms, faster than 100.00%, Memory Usage: 38.7 MB, less than 11.47% of Java online submissions

      // O(N)time
      // O(D)space
      public boolean isSameTree(TreeNode p, TreeNode q) {
          if(p == null) return q == null;
          if(q == null) return p == null;
          return p.val == q.val && isSameTree(p.left, q.left) && isSameTree(p.right, q.right);
      }
      

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