Interview question 02.02 Return the penultimate node

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subject ： Interview questions 02.02. Go back to the last k Nodes
describe ： Implement an algorithm , Find the bottom of the list k Nodes . Returns the value of the node .

Their thinking

1、 Speed pointer ;

Source code ##

class Solution {
    
public:
    int kthToLast(ListNode* head, int k) {
    
        ListNode *slow = head, *fast = head;
        for (int i = 0; i < k; ++i) {
    
            fast = fast->next;
        }
        while (fast) {
    
            fast = fast->next;
            slow = slow->next;
        }
        return slow->val;
    }
};