Tree=0820

//1.doMirror
public void doMirror(TreeNode root) {
    if (root == null || (root.left == null && root.right == null)) {
        return;
    }
    simpleSwap(root);
    doMirror(root.left);
    doMirror(root.right);
}

private void simpleSwap(TreeNode root) {
    TreeNode temp = root.left;
    root.left = root.right;
    root.right = temp;
}

//2.findPath
public void findPath(TreeNode root, int target, List onePath, List<List> pathList) {
    if (root == null) {
        return;
    }
    onePath.add(root.val);
    if (target == root.val && root.left == null && root.right == null) {
        pathList.add(new ArrayList<Integer>(onePath));
    }
    findPath(root.left, target - root.val, onePath, pathList);
    findPath(root.right, target - root.val, onePath, pathList);
    onePath.remove(onePath.size() - 1);
}

//3.isSub
public Boolean isSub(TreeNode rootA, TreeNode rootB) {
    if (rootA == null || rootB == null) {
        return false;
    }
    if (rootA.val == rootB.val && isSame(rootA, rootB)) {
        return true;
    }
    return isSub(rootA.left, rootB) || isSub(rootA.right, rootB);
}

private Boolean isSame(TreeNode rootA, TreeNode rootB) {
    if (rootA == null && rootB == null) {
        return true;
    }
    if (rootA == null || rootB == null || rootA.val != rootB.val) {
        return false;
    }
    return isSame(rootA.left, rootB.left) && isSame(rootA.right, rootB.right);
}

//4.getPath
public int getPath(TreeNode root) {
    if (root == null) {
        return 0;
    }
    return Math.max(getPath(root.left), getPath(root.right)) + 1;
}