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有ios 安卓 C++ Java C#？

第一题 二叉树最近祖先

    public TreeNode lowestCommonAncestor(TreeNode root, TreeNode p, TreeNode q) {
        if (root == null || root == p || root == q) {
            return root;
        }
        TreeNode left = lowestCommonAncestor(root.left, p, q);
        TreeNode right = lowestCommonAncestor(root.right, p, q);
        if (left != null && right != null) {
            return root;
        }
        if (left != null) {
            return left;
        }
        return right;
    }

第二题 统计字符数量

public class Main {

    public static void main(String[] args) {
        Scanner input = new Scanner(System.in);
        String str = input.nextLine();
        int count = 1;
        StringBuilder sb = new StringBuilder();
        for (int i = 0; i < str.length(); i++) {
            while (i < str.length() - 1 && str.charAt(i + 1) == str.charAt(i)) {
                count++;
                i++;
            }
            sb.append(str.charAt(i)).append(count);
            count = 1;
        }
        System.out.println(sb.toString());
    }
}