要求使用一种语言教给最少人数的人，以便所有一对朋友都可以互相交流

给定一个整数N和两个数组A [] [] (表示一个人知道的语言集)，以及B [] [] (由M对友谊组成)，任务是找到要教的最少人数。单一语言，以便每一对朋友都可以相互交流。

例子：

Input: N = 2, A[][] = {{1}, {2}, {1, 2}}, B[][] = {{1, 2}, {1, 3}, {2, 3}}
Output: 1
Explanation:
One possible way is to teach the 1^st person the language 2.
Another possible way is to teach the 2^nd person the language 1.
Therefore, the minimum number of languages required to be taught is 1.

Input: N = 4, A[][] = {{2}, {1, 4}, {1, 2}, {3, 4}}, B[][] = {{1, 4}, {1, 2}, {3, 4}, {2, 3}}
Output: 2
Explanation:
One of the possible way is to teach the 1^st person the language 3 or 4 and the 3^rd person the language 3 or 4.
Therefore, the minimum number of languages required to be taught is 2.

方法：可以使用Set and Map数据结构解决给定问题，从而解决给定问题。
请按照以下步骤解决问题：

• 定义一个函数，例如Check(A []，B []) ，以检查两个排序数组中是否存在任何公共元素：
  • 定义两个变量，例如P1和P2，以存储指针。
  • 在P1 和P2 迭代。如果A [P1]等于B [P2] ，则返回true。否则，如果A [P1] 一个增量P1。否则，如果A [P1]> B [P2]，由1个增量P2。
  • 如果以上情况都不满足，则返回false。
• 初始化一个set ，例如S ，然后一个map ，例如mp ，以存储所有无法与朋友交流的人和知道某种特定语言的人的数量。
• 初始化一个变量，例如result ，以存储要教的人数。
• 遍历数组B [] []并通过调用函数Check(B [i] [0]，B [i] [1])插入一对人，如果他们之间没有共同语言。
• 遍历一个人知道的语言集S并在Map mp中增加该语言的计数。
• 遍历map mp并更新结果为result = min(S.size()– it.second，result)。
• 最后，完成上述步骤后，打印结果。

下面是上述方法的实现：

C++

// C++ implementation of
// the above approach
#include 
using namespace std;
 
// Function to check if there
// exists any common language
bool check(vector& a, vector& b)
{
    // Stores the size of array a[]
    int M = a.size();
 
    // Stores the size of array b[]
    int N = b.size();
 
    // Pointers
    int p1 = 0, p2 = 0;
 
    // Iterate while p1 < M and p2 < N
    while (p1 < M && p2 < N) {
 
        if (a[p1] < b[p2])
            p1++;
        else if (a[p1] > b[p2])
            p2++;
        else
            return true;
    }
    return false;
}
 
// Function to count the minimum number
// of people required to be teached
int minimumTeachings(
    int N, vector >& languages,
    vector > friendships)
{
    // Stores the size of array A[][]
    int m = languages.size();
 
    // Stores the size of array B[][]
    int t = friendships.size();
 
    // Stores all the persons with no
    // common languages with their friends
    unordered_set total;
 
    // Stores count of languages
    unordered_map overall;
 
    // Sort all the languages of
    // a person in ascending order
    for (int i = 0; i < m; i++)
        sort(languages[i].begin(),
             languages[i].end());
 
    // Traverse the array B[][]
    for (int i = 0; i < t; i++) {
        // Check if there is no common
        // language between two friends
        if (!check(languages[friendships[i][0] - 1],
                   languages[friendships[i][1] - 1])) {
 
            // Insert the persons in the Set
            total.insert(friendships[i][0]);
            total.insert(friendships[i][1]);
        }
    }
 
    // Stores the size of the Set
    int s = total.size();
 
    // Stores the count of
    // minimum persons to teach
    int result = s;
 
    // Traverse the set total
    for (auto p : total) {
 
        // Traverse A[p - 1]
        for (int i = 0;
             i < languages[p - 1].size(); i++)
 
            // Increment count of languages by one
            overall[languages[p - 1][i]]++;
    }
 
    // Traverse the map
    for (auto c : overall)
 
        // Update result
        result = min(result, s - c.second);
 
    // Return the result
    return result;
}
 
// Driver Code
int main()
{
    int N = 3;
 
    vector > A
        = { { 1 }, { 1, 3 }, { 1, 2 }, { 3 } };
 
    vector > B
        = { { 1, 4 }, { 1, 2 }, { 3, 4 }, { 2, 3 } };
 
    cout << minimumTeachings(N, A, B) << endl;
 
    return 0;
}

Java

// Java implementation of
// the above approach
import java.io.*;
import java.lang.*;
import java.util.*;
 
class GFG{
 
// Function to check if there
// exists any common language
static boolean check(int a[], int b[])
{
     
    // Stores the size of array a[]
    int M = a.length;
 
    // Stores the size of array b[]
    int N = b.length;
 
    // Pointers
    int p1 = 0, p2 = 0;
 
    // Iterate while p1 < M and p2 < N
    while (p1 < M && p2 < N)
    {
        if (a[p1] < b[p2])
            p1++;
        else if (a[p1] > b[p2])
            p2++;
        else
            return true;
    }
    return false;
}
 
// Function to count the minimum number
// of people required to be teached
static int minimumTeachings(int N, int languages[][],
                            int friendships[][])
{
     
    // Stores the size of array A[][]
    int m = languages.length;
 
    // Stores the size of array B[][]
    int t = friendships.length;
 
    // Stores all the persons with no
    // common languages with their friends
    HashSet total = new HashSet<>();
 
    // Stores count of languages
    HashMap overall = new HashMap<>();
 
    // Sort all the languages of
    // a person in ascending order
    for(int i = 0; i < m; i++)
        Arrays.sort(languages[i]);
 
    // Traverse the array B[][]
    for(int i = 0; i < t; i++)
    {
         
        // Check if there is no common
        // language between two friends
        if (!check(languages[friendships[i][0] - 1],
                   languages[friendships[i][1] - 1]))
        {
             
            // Insert the persons in the Set
            total.add(friendships[i][0]);
            total.add(friendships[i][1]);
        }
    }
 
    // Stores the size of the Set
    int s = total.size();
 
    // Stores the count of
    // minimum persons to teach
    int result = s;
 
    // Traverse the set total
    for(int p : total)
    {
         
        // Traverse A[p - 1]
        for(int i = 0; i < languages[p - 1].length; i++)
         
            // Increment count of languages by one
            overall.put(languages[p - 1][i],
                        overall.getOrDefault(
                            languages[p - 1][i], 0) + 1);
    }
 
    // Traverse the map
    for(int k : overall.keySet())
 
        // Update result
        result = Math.min(result, s - overall.get(k));
 
    // Return the result
    return result;
}
 
// Driver Code
public static void main(String[] args)
{
    int N = 3;
 
    int A[][] = { { 1 }, { 1, 3 },
                  { 1, 2 }, { 3 } };
 
    int B[][] = { { 1, 4 }, { 1, 2 },
                  { 3, 4 }, { 2, 3 } };
 
    System.out.println(minimumTeachings(N, A, B));
}
}
 
// This code is contributed by Kingash

Python3

# Python3 implementation of
# the above approach
 
# Function to check if there
# exists any common language
def check(a, b):
    # Stores the size of array a[]
    M = len(a)
 
    # Stores the size of array b[]
    N = len(b)
 
    # Pointers
    p1 = 0
    p2 = 0
 
    # Iterate while p1 < M and p2 < N
    while(p1 < M and p2 < N):
        if (a[p1] < b[p2]):
            p1 += 1
        elif(a[p1] > b[p2]):
            p2 += 1
        else:
            return True
    return False
 
# Function to count the minimum number
# of people required to be teached
def minimumTeachings(N, languages, friendships):
    # Stores the size of array A[][]
    m = len(languages)
 
    # Stores the size of array B[][]
    t = len(friendships)
 
    # Stores all the persons with no
    # common languages with their friends
    total = set()
 
    # Stores count of languages
    overall = {}
 
    # Sort all the languages of
    # a person in ascending order
    for i in range(m):
        languages[i].sort(reverse=False)
 
    # Traverse the array B[][]
    for i in range(t):
        # Check if there is no common
        # language between two friends
        if(check(languages[friendships[i][0] - 1], languages[friendships[i][1] - 1])==False):
            # Insert the persons in the Set
            total.add(friendships[i][0])
            total.add(friendships[i][1])
 
    # Stores the size of the Set
    s = len(total)
 
    # Stores the count of
    # minimum persons to teach
    result = s
 
    # Traverse the set total
    for p in total:
        # Traverse A[p - 1]
        for i in range(len(languages[p - 1])):
            # Increment count of languages by one
            if languages[p - 1][i] in overall:
              overall[languages[p - 1][i]] += 1
            else:
              overall[languages[p - 1][i]] = 1
 
    # Traverse the map
    for keys,value in overall.items():
        # Update result
        result = min(result, s - value)
 
    # Return the result
    return result
 
# Driver Code
if __name__ == '__main__':
    N = 3
 
    A =   [[1],[1, 3],[1, 2],[3]]
    B =  [[1, 4],[1, 2],[3, 4],[2, 3]]
    print(minimumTeachings(N, A, B))
     
    # This code is contributed by ipg2016107.

输出：

1

时间复杂度： O(N ² )
辅助空间： O(N)