题解 | #二叉树根节点到叶子节点的所有路径和#

使用栈

import java.util.*;

/*
 * public class ListNode {
 *   int val;
 *   ListNode next = null;
 *   public ListNode(int val) {
 *     this.val = val;
 *   }
 * }
 */

public class Solution {
      public ListNode FindKthToTail (ListNode pHead, int k) {
        if(pHead==null||k==0) return null;
        
        Stack<ListNode> stack = new Stack<>();//放入栈中
        stack.push(pHead);
        while(pHead.next != null){
            stack.push(pHead.next);
            pHead = pHead.next;
        }

        if(stack.size()<k) return null;
          
        for (int i=0; i<k-1; i++) {
            stack.pop();
        }
        return stack.pop();
    }
}