LeetCode Hot 100 P160 Intersection of Two Linked Lists

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Timeline

Timeline

2026-03-13

init

linked list

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Problem:

P160 Intersection of Two Linked Lists

https://leetcode.cn/problems/intersection-of-two-linked-lists/description/?envType=study-plan-v2&envId=top-100-liked

Align your orbit with hers, and you will meet eventually~

/**
 * Definition for singly-linked list.
 * struct ListNode {
 *     int val;
 *     ListNode *next;
 *     ListNode(int x) : val(x), next(NULL) {}
 * };
 */

#include <cstdlib>

struct ListNode {
        int val;
        ListNode *next;
        ListNode(int x)
                : val(x)
                , next(nullptr)
        {
        }
};

class Solution {
    public:
        ListNode *getIntersectionNode(ListNode *headA, ListNode *headB)
        {
                int linkA_len = 1, linkB_len = 1, offset;
                ListNode *p = headA, *q = headB;

                while (p->next != nullptr) {
                        p = p->next;
                        linkA_len++;
                }

                while (q->next != nullptr) {
                        q = q->next;
                        linkB_len++;
                }

                if (p != q) // Two linked lists that do not intersect
                        return nullptr;

                offset = std::abs(linkA_len - linkB_len);
                p = headA;
                q = headB;
                if (linkA_len > linkB_len) {
                        for (int i = 0; i < offset; i++)
                                p = p->next;

                } else {
                        for (int i = 0; i < offset; i++)
                                q = q->next;
                }

                while (p != q) {
                        p = p->next;
                        q = q->next;
                }
                return p;
        }
};