Codeforces 432A Choosing Teams Solution & Explanation

Difficulty : 800

Problem Description

The Saratov State University Olympiad Programmers Training Center (SSU OPTC) has n students. For each student you know the number of times he/she has participated in the ACM ICPC world programming championship. According to the ACM ICPC rules, each person can participate in the world championship at most 5 times.

The head of the SSU OPTC is recently gathering teams to participate in the world championship. Each team must consist of exactly three people, at that, any person cannot be a member of two or more teams. What maximum number of teams can the head make if he wants each team to participate in the world championship with the same members at least k times?

Input

The first line contains two integers, n and k (1 ≤ n ≤ 2000; 1 ≤ k ≤ 5). The next line contains n integers: y₁, y₂, …, y_n (0 ≤ y_i ≤ 5), where y_i shows the number of times the i-th person participated in the ACM ICPC world championship.

Output

Print a single number — the answer to the problem.

Examples

Note

In the first sample only one team could be made: the first, the fourth and the fifth participants.

In the second sample no teams could be created.

In the third sample two teams could be created. Any partition into two teams fits.

Solution

First, we need to count the number of students who have enough remaining participation times.

Then, we will calculate how many teams they can form (3 students per team).

C# Solution

Solution1 – count by LINQ

int[] arr = Console.ReadLine().Split(' ').Select(int.Parse).ToArray();

int n = arr[0];
int k = arr[1];

int[] students = Console.ReadLine().Split(' ').Select(int.Parse).ToArray();

// Check if each student has sufficient participation times remaining
int cnt = students.Count(x=>x+k<=5);

Console.WriteLine(cnt/3);

Solution2 – for loop

int[] arr = Console.ReadLine().Split(' ').Select(int.Parse).ToArray();

int n = arr[0];
int k = arr[1];

int[] students = Console.ReadLine().Split(' ').Select(int.Parse).ToArray();

//the number of students who have enough remaining participation times
int cnt = 0;

foreach(var curr in students){
    if(curr+k<=5){
        cnt+=1;
    }
}

Console.WriteLine(cnt/3);

Java Solution

Solution1

import java.util.Scanner;
import java.util.Arrays;

public class Main {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        int[] arr = Arrays.stream(scanner.nextLine().split(" "))
                               .mapToInt(Integer::parseInt)
                               .toArray();
        int n = arr[0];
        int k = arr[1];
        
        int[] students = Arrays.stream(scanner.nextLine().split(" "))
                       .mapToInt(Integer::parseInt)
                       .toArray();
        
        //the number of students who have enough remaining participation times
        int cnt = 0;
        
        for(int curr : students){
            if(curr+k<=5){
                cnt+=1;
            }
        }
        
        System.out.println(cnt/3);
    }
}

Conclusion

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The problem link : Problem – 432A – Codeforces

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