C++ 中从两个链表中统计对数,使其和等于给定值


给定两个链表,任务是使用链表的整数元素形成对,使得它们的和等于给定值,假设为 k。链表是由链接连接在一起的数据结构序列。

输入

vector v_1 = {5, 7, 8, 10, 11},.
vector v_2 = {6, 4, 3, 2, 0} , int k = 11

输出

Count of pairs from two linked lists whose sum is equal to a given value k are: 4

解释

The pairs which can be formed using the given linked lists are: (5, 6) = 11(equals to k), (5, 4) = 9(not equals to k), (5, 3) = 8(not equals to k), (5, 2) = 7(not equals to k), (5, 0) = 5(not equals to k), (7, 6) = 13(not equals to k), (7, 4) = 11(equals to k), (7, 3) = 10(not equals to k), (7, 2) = 9(not equals to k), (7, 0) = 7(not equals to k), (8, 6) = 14(not equals to k), (8, 4) = 12(not equals to k), (8, 3) = 11(equals to k), (8, 2) = 10(not equals to k), (8, 0) = 8(not equals to k), (10, 6) = 16(not equals to k), (10, 4) = 14(not equals to k), (10, 3) = 13(not equals to k), (10, 2) = 12(not equals to k), (10, 0) = 10(not equals to k), (11, 6) = 17(not equals to k), (11, 4) = 15(not equals to k), (11, 3) = 14(not equals to k), (11, 2) = 13(not equals to k), (11, 0) = 11(not equals to k). So, clearly there are 3 pairs which are equal to the given sum.

输入

vector v_1 = {2, 3, 5, 6},.
vector v_2 = {6, 4, 3} , int k = 6

输出

Count of pairs from two linked lists whose sum is equal to a given value k are: 2

解释

The pairs which can be formed using the given linked lists are: (2, 6) = 8(not equals to k), (2, 4) = 6(equals to k), (2, 3) = 5(not equals to k), (3, 6) = 9(not equals to k), (3, 4) = 7(not equals to k), (3, 3) = 6(equals to k), (5, 6) = 11(not equals to k), (5, 4) = 9(not equals to k), (5, 3) = 8(not equals to k), (6, 6) = 12(not equals to k), (6, 4) = 10(not equals to k), (6, 3) = 9(not equals to k),. So, clearly there are 2 pairs which are equal to the given sum.

下面程序中使用的方案如下

  • 输入 k 的值和整数类型的值到两个向量中,以便我们可以将向量传递以形成链表。

  • 创建一个函数,该函数将使用作为参数传递给函数的向量来创建一个链表。

  • 遍历循环直到向量的尺寸,并创建一个类指针对象

    ListNode

    • 遍历循环,直到 ptr->next 不等于 NULL,并将 ptr 设置为 ptr->next

    • 在 ptr->next 中设置 vector[i]

    • 返回开始

  • 创建一个函数,该函数将返回与给定总和匹配的对的数量。

    • 取一个临时变量 count 并将其设置为 0

    • 创建两个指针对象,即 *first_list 用于第一个链表,*second_list 用于第二个链表。

    • 从第一个列表的起始指针开始循环,直到列表为空。

    • 在循环内,从第二个列表的起始指针开始另一个循环,直到列表为空。

    • 在循环内,检查 IF (first_list->data + second_list->data) == k,然后将 count 增加 1。

    • 返回计数

  • 打印结果。

示例

实时演示

#include<bits/stdc++.h>
using namespace std;
class ListNode{
public:
   int data;
   ListNode *next;
   ListNode(int data){
      this->data = data;
      next = NULL;
   }
};
ListNode *CreateList(vector v){
   ListNode *start = new ListNode(v[0]);
   for (int i = 1; i < v.size(); i++){
      ListNode *ptr = start;
      while (ptr->next != NULL){
         ptr = ptr->next;
      }
      ptr->next = new ListNode(v[i]);
   }
   return start;
}
int sum_pair(ListNode *start_1, ListNode *start_2, int k){
   int count = 0;
   ListNode *first_list , *second_list;
   for (first_list = start_1; first_list != NULL; first_list = first_list->next){
      for (second_list = start_2; second_list != NULL; second_list = second_list->next){
         if ((first_list->data + second_list->data) == k){
            count++;
         }
      }
   }
   return count;
}
int main(){
   vector<int> v_1 = {5, 7, 8, 10, 11};
   ListNode* start_1 = CreateList(v_1);
   vector v_2 = {6, 4, 3, 2, 0};
   ListNode* start_2 = CreateList(v_2);
   int k = 11;
   cout<<"Count of pairs from two linked lists whose sum is equal to a given value k are: "<<sum_pair(start_1, start_2, k);
}

输出

如果我们运行以上代码,它将生成以下输出:

Count of pairs from two linked lists whose sum is equal to a given value k are: 4

更新于: 2020年11月2日

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