练习

LeetCode:226. 翻转二叉树

解一

var invertTree = function (root) {
    if (!root) return null
    let q = [root];
    for (let i = 0; i < q.length; i++) {
        let n = q[i];
        let temp = n.left;
        n.left = n.right;
        n.right = temp;
        n.right && q.push(n.right);
        n.left && q.push(n.left)
    }
    return root;
};

解二

var invertTree = function (root) {
    if (!root) return null
    return {
        val:root.val,
        right:invertTree(root.left),
        left:invertTree(root.right)
    }
};

LeetCode:100. 相同的树

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

LeetCode:101. 对称二叉树

var isSymmetric = function (root) {
    if (!root) return true

    const isMirror = (l, r) => {
        if(!l && !r) return true;
        if (
            l && r &&
            l.val === r.val
            &&
            isMirror(l.left, r.right)
            &&
            isMirror(l.right, r.left)
        ) {
            return true
        }
        return false
    }
    return isMirror(root.left, root.right)
};