剑指Offer-37

来源：互联网发布：大学生程序员怎么赚钱编辑：程序博客网时间：2024/05/21 05:07
题目：

输入两个链表，找出这两个链表的第一个公共结点。
实现

// coding = javapublic class Solution37 {    public static Node findCommonNode(Node head1,Node head2){        if(head1 == null || head2==null){            return null;        }        Node long_list = head1;        Node short_list = head2;        int length1 = getLength(head1);        int length2 = getLength(head2);        int diff = length1 - length2;        if(length2>length1){            long_list = head2;            short_list = head1;            diff = length2-length1;        }        for(int i=0;i<diff;i++){            long_list = long_list.next;        }        while (long_list!=null && short_list!=null && long_list!=short_list){            long_list = long_list.next;            short_list = short_list.next;        }        return long_list;    }    public static int getLength(Node head){        Node index = head;        int length = 0;        while(index!=null){            index = index.next;            length++;        }        return length;    }    public static void main(String[] args) {        test1();        test2();        test3();        test4();    }    private static void test1() {        // 第一个公共结点在链表中间        // 1 - 2 - 3 \        //            6 - 7        //     4 - 5 /        Node n1 = new Node(1);        Node n2 = new Node(2);        Node n3 = new Node(3);        Node n4 = new Node(4);        Node n5 = new Node(5);        Node n6 = new Node(6);        Node n7 = new Node(7);        n1.next = n2;        n2.next = n3;        n3.next = n6;        n6.next = n7;        n4.next = n5;        n5.next = n6;        Node result = findCommonNode(n1, n4);        if (result != null) {            System.out.println(result.value); // 6        }    }    private static void test2() {        // 没有公共结点        // 1 - 2 - 3 - 4        //        // 5 - 6 - 7        Node n1 = new  Node(1);        Node n2 = new  Node(2);        Node n3 = new  Node(3);        Node n4 = new  Node(4);        Node n5 = new  Node(5);        Node n6 = new Node(6);        Node n7 = new Node(7);        n1.next = n2;        n2.next = n3;        n3.next = n4;        n5.next = n6;        n6.next = n7;        Node result = findCommonNode(n1, n5);        if (result != null) {            System.out.println(result.value); // null        }    }    private static void test3() {        // 公共结点是最后一个结点        // 1 - 2 - 3 - 4 \        //                7        //         5 - 6 /        Node n1 = new Node(1);        Node n2 = new Node(2);        Node n3 = new Node(3);        Node n4 = new Node(4);        Node n5 = new Node(5);        Node n6 = new Node(6);        Node n7 = new Node(7);        n1.next = n2;        n2.next = n3;        n3.next = n4;        n4.next = n7;        n5.next = n6;        n6.next = n7;        Node result = findCommonNode(n1, n5);        if (result != null) {            System.out.println(result.value);  // 7        }    }    private static void test4() {        // 公共结点是第一个结点        // 1 - 2 - 3 - 4 - 5        // 两个链表完全重合        Node n1 = new Node(1);        Node n2 = new Node(2);        Node n3 = new Node(3);        Node n4 = new Node(4);        Node n5 = new Node(5);        Node n6 = new Node(6);        Node n7 = new Node(7);        n1.next = n2;        n2.next = n3;        n3.next = n4;        n4.next = n5;        Node result = findCommonNode(n1, n1);        if (result != null) {            System.out.println(result.value); // 1        }    }}
阅读全文
0 0