Data Structure Linked List: Write a function to get the intersection point of two Linked Lists.

http://www.geeksforgeeks.org/write-a-function-to-get-the-intersection-point-of-two-linked-lists/

第一第二个方法比较简单，下面这段代码是第三个方法

#include <iostream>
#include <vector>
#include <algorithm>
#include <queue>
#include <stack>
#include <string>
#include <fstream>
#include <map>
#include <set>
using namespace std;

struct node {
    int data;
    node *next;
    node() : data(0), next(NULL) { }
    node(int d) : data(d), next(NULL) { }
};

void push(node* &head, int k) {
    node *new_node = new node(k);
    new_node->next = head;
    head = new_node;
}

void print(node* head) {
    while (head) {
        cout << head->data << " ";
        head = head->next;
    }
    cout << endl;
}

int getintersect(node *first, node *second) {
    int c1 = 0;
    int c2 = 0;
    node *p = first;
    while (p) {
        c1++;
        p = p->next;
    }
    p = second;
    while (p) {
        c2++;
        p = p->next;
    }
    if (c1 < c2) {
        swap(c1, c2);
        swap(first, second);
    }
    while (c1 != c2) {
        c1--;
        first = first->next;
    }
    while (first != second) {
        first = first->next;
        second = second->next;
    }
    return second->data;
}

int main() {
    node *head = new node(3);
    head->next = new node(6);
    head->next->next = new node(9);
    head->next->next->next = new node(15);
    head->next->next->next->next = new node(30);
    node *second = new node(10);
    second->next = head->next->next->next;
    cout << getintersect(head, second);
    return 0;
}

 第四第五个方法不太容易想到