package com.zmz.algorithm.listnode;

import java.util.List;

/**
 * @author 张明泽
 * Create by 2022/5/29 15:39
 * 链表相交
 * 面试题02.07=链表相交
 */
public class ListIntersection {
    public static void main(String[] args) {
        ListNode head1 = new ListNode(4);
        ListNode node2 = new ListNode(1);
        ListNode node3 = new ListNode(8);
        ListNode node4 = new ListNode(4);
        ListNode node5 = new ListNode(5);
        head1.next = node2;
        node2.next = node3;
        node3.next = node4;
        node4.next = node5;

        ListNode head11 = new ListNode(5);
        ListNode node22 = new ListNode(0);
        ListNode node33 = new ListNode(1);
        head11.next = node22;
        node22.next = node33;
        node33.next = node3;
        node3.next = node4;
        node4.next = node5;
        ListNode result = interSection(head1,head11);
        traverse(result);
    }

    /**
     * 让长的先走完长度差(这样就并排一起走)
     */
    public static ListNode interSection(ListNode listNodeA, ListNode listNodeB) {
        ListNode headA = listNodeA;
        ListNode headB = listNodeB;
        int sizeA = 0;
        int sizeB = 0;
        // 分别求长度
        while (headA != null) {
            sizeA++;
            headA = headA.next;
        }
        while (headB != null) {
            sizeB++;
            headB = headB.next;
        }
        // 重新指向首节点
        headA = listNodeA;
        headB = listNodeB;

        int difference = Math.abs(sizeA - sizeB);
        // 让长的走个差值 这样可以达到并排走的效果
        for (int i = 0; i < difference; i++) {
            if (sizeA > sizeB) {
                headA = headA.next;
            } else if (sizeA < sizeB){
                headB = headB.next;
            }
        }
        while (headA != null) {
            if (headA == headB) {
                return headA;
            }
            headA = headA.next;
            headB = headB.next;
        }
        return null;
    }
    public static class ListNode {
        int val;
        ListNode next;
        ListNode() {}
        ListNode(int val) { this.val = val; }
        ListNode(int val, ListNode next) { this.val = val; this.next = next; }
    }
    public static void traverse(ListNode listNode) {
        while (listNode != null) {
            System.out.println(listNode.val);
            listNode = listNode.next;
        }
    }
}