题目描述

输入两个链表，找出它们的第一个公共结点。

分析

考虑到两个链表不一样长的情况，算出两个链表的长度差，然后长的链表要先把长度差走完，然后两个链表再一起走。

代码实现

/*function ListNode(x){    this.val = x;    this.next = null;}*/function FindFirstCommonNode(h1, h2){    var h1Len = 0, h2Len = 0;    var cur = h1;        while(cur!==null){        h1Len++;        cur = cur.next;    }        cur = h2;    while(cur!==null){        h2Len++;        cur = cur.next;    }        var distance = 0;    var t1, t2;    if(h1Len > h2Len){        t1 = h1;        t2 = h2;        distance = h1Len - h2Len;    }else{        t1 = h2;        t2 = h1;        distance = h2Len - h1Len;    }        while(distance !== 0){        t1 = t1.next;        distance--;    }        while(t1 !== t2){        t1 = t1.next;        t2 = t2.next;    }        return t1;}