剑指offer第4题：从头到尾打印链表

class Solution {
    public int[] reversePrint(ListNode head) {
        ListNode pre = null;
        int size = 0;//记录链表长度
        while(head != null){//反转链表
            ListNode temp = head.next;
            head.next = pre;
            pre = head;
            head = temp;
            size++;
        }
        int[] ans = new int[size];
        for(int i = 0 ; i < size ; i++){//构建返回数组
            ans[i] = pre.val;
            pre = pre.next;
        }
        return ans;
    }
}

public  int[] reversePrint(ListNode head) {
    Stack<Integer> stack = new Stack<>();
    while(head != null){
        stack.push(head.val);
        head = head.next;
    }
    int size = stack.size();
    int[] ans = new int[size];
    for(int i = 0 ; i < size ; i++){
        ans[i] = stack.pop();
    }
    return ans;
}