LeetCode Same Tree OJ 算法 刷题

Same Tree

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


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

Solution

[code]public class SameTree {
    public static void main(String[] args) {
        TreeNode r0 = new TreeNode(00);
        TreeNode r11 = new TreeNode(11);
        TreeNode r12 = new TreeNode(12);
        TreeNode r21 = new TreeNode(21);
        TreeNode r31 = new TreeNode(31);
        r0.left = r11;
        r0.right = r12;
        r11.left = r21;
        r21.left = r31;

        TreeNode rr0 = new TreeNode(00);
        TreeNode rr11 = new TreeNode(11);
        TreeNode rr12 = new TreeNode(12);
        TreeNode rr21 = new TreeNode(21);
        TreeNode rr31 = new TreeNode(31);
        rr0.left = rr11;
        rr0.right = rr12;
        rr11.left = r21;
        rr21.left = rr31;

        System.out.println(isSameTree(rr31, r31));

    }

    public static boolean isSameTree(TreeNode p, TreeNode q) {
        if (p == null && q == null)
            return true;
        if (p == null)
            return false;
        if (q == null)
            return false;

        if (p.val != q.val) {
            return false;
        }
        return isSameTree(p.left, q.left) && isSameTree(p.right, q.right);

    }
}

[code]class TreeNode {
    int val;
    TreeNode left;
    TreeNode right;

    TreeNode(int x) {
    val = x;
    }
}