LeetCode（剑指 Offer）- 06. 从尾到头打印链表

题目链接：​​点击打开链接​​

题目大意：略。

解题思路：略。

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• 字节跳动

AC 代码

• Java

/**
 * Definition for singly-linked list.
 * public class ListNode {
 *     int val;
 *     ListNode next;
 *     ListNode(int x) { val = x; }
 * }
 */
// 解决方案(1)
class Solution {
    public int[] reversePrint(ListNode head) {
        int i = 0;
        ListNode p = head;
        while (null != p) {
            p = p.next;
            i++;
        }

        int[] arr = new int[i];
        while (null != head) {
            arr[--i] = head.val;
            head = head.next;
        }

        return arr;
    }
}

// 解决方案(2)
class Solution {
    ArrayList<Integer> tmp = new ArrayList<Integer>();
    public int[] reversePrint(ListNode head) {
        recur(head);
        int[] res = new int[tmp.size()];
        for(int i = 0; i < res.length; i++)
            res[i] = tmp.get(i);
        return res;
    }
    void recur(ListNode head) {
        if(head == null) return;
        recur(head.next);
        tmp.add(head.val);
    }
}

// 解决方案(3)
class Solution {
    public int[] reversePrint(ListNode head) {
        LinkedList<Integer> stack = new LinkedList<Integer>();
        while(head != null) {
            stack.addLast(head.val);
            head = head.next;
        }
        int[] res = new int[stack.size()];
        for(int i = 0; i < res.length; i++)
            res[i] = stack.removeLast();
    return res;
    }
}

• C++

// 解决方案(1)
class Solution {
public:
    vector<int> reversePrint(ListNode* head) {
        recur(head);
        return res;
    }
private:
    vector<int> res;
    void recur(ListNode* head) {
        if(head == nullptr) return;
        recur(head->next);
        res.push_back(head->val);
    }
};

// 解决方案(2)
class Solution {
public:
    vector<int> reversePrint(ListNode* head) {
        stack<int> stk;
        while(head != nullptr) {
            stk.push(head->val);
            head = head->next;
        }
        vector<int> res;
        while(!stk.empty()) {
            res.push_back(stk.top());
            stk.pop();
        }
        return res;
    }
};