Niuke-top101-bm38

import java.util.*;

/* * public class TreeNode { * int val = 0; * TreeNode left = null; * TreeNode right = null; * } */

public class Solution {
    
    /** * * @param root TreeNode class  * @param o1 int integer  * @param o2 int integer  * @return int integer  */
    boolean sign = false;
    public int lowestCommonAncestor (TreeNode root, int o1, int o2) {
    
        // write code here
        ArrayList<Integer> list1 = new ArrayList<>();
        ArrayList<Integer> list2 = new ArrayList<>();
        dfs(root, o1, list1);
        sign = false;
        dfs(root, o2, list2);
        int res = 0;
        for(int i = 0; i < list1.size() && i < list2.size(); i++){
    
            int x = list1.get(i);
            int y = list2.get(i);
            if(x == y){
    
                res = list1.get(i);
            }else{
    
                break;
            }
        }
        return res;
    }
    
    public void dfs(TreeNode root, int target, ArrayList<Integer> path){
    
        // Sentenced to empty 
        if(root == null || sign == true)
            return;
        path.add(root.val);
        if(root.val == target){
    
            sign = true;
            return;
        }
        //dfs Traverse 
        dfs(root.left, target, path);
        dfs(root.right, target, path);
        
        if(sign == true)
            return;
        // to flash back 
        path.remove(path.size() - 1);
    }
}